๐๐จ๐ฆ๐ ๐๐๐ฌ๐ญ ๐ฉ๐ซ๐๐๐ญ๐ข๐๐๐ฌ ๐ญ๐จ ๐ก๐๐ฅ๐ฉ ๐ฒ๐จ๐ฎ ๐จ๐ฉ๐ญ๐ข๐ฆ๐ข๐ณ๐ ๐ฒ๐จ๐ฎ๐ซ ๐๐๐ ๐ช๐ฎ๐๐ซ๐ข๐๐ฌ:
1. Simplify Joins
โข Decompose complex joins into simpler, more manageable queries when possible.
โข Index columns that are used as foreign keys in joins to enhance join performance.
2. Query Structure Optimization
โข Apply WHERE clauses as early as possible to filter out rows before they are processed further.
โข Utilize LIMIT or TOP clauses to restrict the number of rows returned, which can significantly reduce processing time.
3. Partition Large Tables
โข Divide large tables into smaller, more manageable partitions.
โข Ensure that each partition is properly indexed to maintain query performance.
4. Optimize SELECT Statements
โข Limit the columns in your SELECT clause to only those you need. Avoid using SELECT * to prevent unnecessary data retrieval.
โข Prefer using EXISTS over IN for subqueries to improve query performance.
5. Use Temporary Tables Wisely
โข Temporary Tables: Use temporary tables to save intermediate results when you have a complex query. This helps break down a complicated query into simpler steps, making it easier to manage and faster to run.
6. Optimize Table Design
โข Normalize your database schema to eliminate redundant data and improve consistency.
โข Consider denormalization for read-heavy systems to reduce the number of joins needed.
7. Avoid Correlated Subqueries
โข Replace correlated subqueries with joins or use derived tables to improve performance.
โข Correlated subqueries can be very inefficient as they are executed multiple times.
8. Use Stored Procedures:
โข Put complicated database tasks into stored procedures. These are pre-written sets of instructions saved in the database. They make your queries run faster because the database doesnโt have to figure out how to execute them each time
SQL Resources: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
1. Simplify Joins
โข Decompose complex joins into simpler, more manageable queries when possible.
โข Index columns that are used as foreign keys in joins to enhance join performance.
2. Query Structure Optimization
โข Apply WHERE clauses as early as possible to filter out rows before they are processed further.
โข Utilize LIMIT or TOP clauses to restrict the number of rows returned, which can significantly reduce processing time.
3. Partition Large Tables
โข Divide large tables into smaller, more manageable partitions.
โข Ensure that each partition is properly indexed to maintain query performance.
4. Optimize SELECT Statements
โข Limit the columns in your SELECT clause to only those you need. Avoid using SELECT * to prevent unnecessary data retrieval.
โข Prefer using EXISTS over IN for subqueries to improve query performance.
5. Use Temporary Tables Wisely
โข Temporary Tables: Use temporary tables to save intermediate results when you have a complex query. This helps break down a complicated query into simpler steps, making it easier to manage and faster to run.
6. Optimize Table Design
โข Normalize your database schema to eliminate redundant data and improve consistency.
โข Consider denormalization for read-heavy systems to reduce the number of joins needed.
7. Avoid Correlated Subqueries
โข Replace correlated subqueries with joins or use derived tables to improve performance.
โข Correlated subqueries can be very inefficient as they are executed multiple times.
8. Use Stored Procedures:
โข Put complicated database tasks into stored procedures. These are pre-written sets of instructions saved in the database. They make your queries run faster because the database doesnโt have to figure out how to execute them each time
SQL Resources: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐2โค1
A lot of people struggle with SQL Joins.
The truth is, once you've grasped it, you won't forget it.
Here's my super simple breakdown of common SQL joins:
To start, let's quickly cover what a join is in SQL.
Data can be stored in RDMS which means relational database management systems.
Being relational indicates data in tables can relate to each other.
To relate data we need to join it.
When working with data, there are 2 types of joins that you will use more than any other.
Let's get into it...
For this post let's pretend we have 2 tables: table 1 and table 2.
Join 1: Left join
Left join simply means we take all rows from table 1 and look at table 2 for any matches based on a field (or fields).
If there is a match, we return every row from table 1 with the matching row from table 2. If there is no match the result from table 2 will be NULL.
Join 2: Inner join
Now, let's look at the inner join.
Inner join identifies and selects records that have matching values in both tables.
Picture it like a Venn diagram, where only the overlapping area, representing the common values, is selected.
This means that if there's no match between the tables based on the specified fields, those rows won't be included in the result set.
Remember left join returns ALL rows from table 1 so the number of rows wont change pre vs post join (assuming no duplicate values).
With inner join this is slightly different, the number of rows CAN change because we are only looking for matches in both tables.
And there you have it, my super simple breakdown of the most common SQL joins.
If you learned something from this, give this post a like
The truth is, once you've grasped it, you won't forget it.
Here's my super simple breakdown of common SQL joins:
To start, let's quickly cover what a join is in SQL.
Data can be stored in RDMS which means relational database management systems.
Being relational indicates data in tables can relate to each other.
To relate data we need to join it.
When working with data, there are 2 types of joins that you will use more than any other.
Let's get into it...
For this post let's pretend we have 2 tables: table 1 and table 2.
Join 1: Left join
Left join simply means we take all rows from table 1 and look at table 2 for any matches based on a field (or fields).
If there is a match, we return every row from table 1 with the matching row from table 2. If there is no match the result from table 2 will be NULL.
Join 2: Inner join
Now, let's look at the inner join.
Inner join identifies and selects records that have matching values in both tables.
Picture it like a Venn diagram, where only the overlapping area, representing the common values, is selected.
This means that if there's no match between the tables based on the specified fields, those rows won't be included in the result set.
Remember left join returns ALL rows from table 1 so the number of rows wont change pre vs post join (assuming no duplicate values).
With inner join this is slightly different, the number of rows CAN change because we are only looking for matches in both tables.
And there you have it, my super simple breakdown of the most common SQL joins.
If you learned something from this, give this post a like
๐9๐2โค1
Top interview SQL questions, including both technical and non-technical questions, along with their answers PART-1
1. What is SQL?
- Answer: SQL (Structured Query Language) is a standard programming language specifically designed for managing and manipulating relational databases.
2. What are the different types of SQL statements?
- Answer: SQL statements can be classified into DDL (Data Definition Language), DML (Data Manipulation Language), DCL (Data Control Language), and TCL (Transaction Control Language).
3. What is a primary key?
- Answer: A primary key is a field (or combination of fields) in a table that uniquely identifies each row/record in that table.
4. What is a foreign key?
- Answer: A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. It establishes a link between the data in two tables.
5. What are joins? Explain different types of joins.
- Answer: A join is an SQL operation for combining records from two or more tables. Types of joins include INNER JOIN, LEFT JOIN (or LEFT OUTER JOIN), RIGHT JOIN (or RIGHT OUTER JOIN), and FULL JOIN (or FULL OUTER JOIN).
6. What is normalization?
- Answer: Normalization is the process of organizing data to reduce redundancy and improve data integrity. This typically involves dividing a database into two or more tables and defining relationships between them.
7. What is denormalization?
- Answer: Denormalization is the process of combining normalized tables into fewer tables to improve database read performance, sometimes at the expense of write performance and data integrity.
8. What is stored procedure?
- Answer: A stored procedure is a prepared SQL code that you can save and reuse. So, if you have an SQL query that you write frequently, you can save it as a stored procedure and then call it to execute it.
9. What is an index?
- Answer: An index is a database object that improves the speed of data retrieval operations on a table at the cost of additional storage and maintenance overhead.
10. What is a view in SQL?
- Answer: A view is a virtual table based on the result set of an SQL query. It contains rows and columns, just like a real table, but does not physically store the data.
11. What is a subquery?
- Answer: A subquery is an SQL query nested inside a larger query. It is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.
12. What are aggregate functions in SQL?
- Answer: Aggregate functions perform a calculation on a set of values and return a single value. Examples include COUNT, SUM, AVG (average), MIN (minimum), and MAX (maximum).
13. Difference between DELETE and TRUNCATE?
- Answer: DELETE removes rows one at a time and logs each delete, while TRUNCATE removes all rows in a table without logging individual row deletions. TRUNCATE is faster but cannot be rolled back.
14. What is a UNION in SQL?
- Answer: UNION is an operator used to combine the result sets of two or more SELECT statements. It removes duplicate rows between the various SELECT statements.
15. What is a cursor in SQL?
- Answer: A cursor is a database object used to retrieve, manipulate, and navigate through a result set one row at a time.
16. What is trigger in SQL?
- Answer: A trigger is a set of SQL statements that automatically execute or "trigger" when certain events occur in a database, such as INSERT, UPDATE, or DELETE.
17. Difference between clustered and non-clustered indexes?
- Answer: A clustered index determines the physical order of data in a table and can only be one per table. A non-clustered index, on the other hand, creates a logical order and can be many per table.
18. Explain the term ACID.
- Answer: ACID stands for Atomicity, Consistency, Isolation, and Durability.
SQL Resources: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Hope it helps :)
1. What is SQL?
- Answer: SQL (Structured Query Language) is a standard programming language specifically designed for managing and manipulating relational databases.
2. What are the different types of SQL statements?
- Answer: SQL statements can be classified into DDL (Data Definition Language), DML (Data Manipulation Language), DCL (Data Control Language), and TCL (Transaction Control Language).
3. What is a primary key?
- Answer: A primary key is a field (or combination of fields) in a table that uniquely identifies each row/record in that table.
4. What is a foreign key?
- Answer: A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. It establishes a link between the data in two tables.
5. What are joins? Explain different types of joins.
- Answer: A join is an SQL operation for combining records from two or more tables. Types of joins include INNER JOIN, LEFT JOIN (or LEFT OUTER JOIN), RIGHT JOIN (or RIGHT OUTER JOIN), and FULL JOIN (or FULL OUTER JOIN).
6. What is normalization?
- Answer: Normalization is the process of organizing data to reduce redundancy and improve data integrity. This typically involves dividing a database into two or more tables and defining relationships between them.
7. What is denormalization?
- Answer: Denormalization is the process of combining normalized tables into fewer tables to improve database read performance, sometimes at the expense of write performance and data integrity.
8. What is stored procedure?
- Answer: A stored procedure is a prepared SQL code that you can save and reuse. So, if you have an SQL query that you write frequently, you can save it as a stored procedure and then call it to execute it.
9. What is an index?
- Answer: An index is a database object that improves the speed of data retrieval operations on a table at the cost of additional storage and maintenance overhead.
10. What is a view in SQL?
- Answer: A view is a virtual table based on the result set of an SQL query. It contains rows and columns, just like a real table, but does not physically store the data.
11. What is a subquery?
- Answer: A subquery is an SQL query nested inside a larger query. It is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.
12. What are aggregate functions in SQL?
- Answer: Aggregate functions perform a calculation on a set of values and return a single value. Examples include COUNT, SUM, AVG (average), MIN (minimum), and MAX (maximum).
13. Difference between DELETE and TRUNCATE?
- Answer: DELETE removes rows one at a time and logs each delete, while TRUNCATE removes all rows in a table without logging individual row deletions. TRUNCATE is faster but cannot be rolled back.
14. What is a UNION in SQL?
- Answer: UNION is an operator used to combine the result sets of two or more SELECT statements. It removes duplicate rows between the various SELECT statements.
15. What is a cursor in SQL?
- Answer: A cursor is a database object used to retrieve, manipulate, and navigate through a result set one row at a time.
16. What is trigger in SQL?
- Answer: A trigger is a set of SQL statements that automatically execute or "trigger" when certain events occur in a database, such as INSERT, UPDATE, or DELETE.
17. Difference between clustered and non-clustered indexes?
- Answer: A clustered index determines the physical order of data in a table and can only be one per table. A non-clustered index, on the other hand, creates a logical order and can be many per table.
18. Explain the term ACID.
- Answer: ACID stands for Atomicity, Consistency, Isolation, and Durability.
SQL Resources: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Hope it helps :)
๐10โค2
SQL can be simpleโif you learn it the smart way..
If youโre aiming to become a data analyst, mastering SQL is non-negotiable.
Hereโs a smart roadmap to ace it:
1. Basics First: Understand data types, simple queries (SELECT, FROM, WHERE). Master basic filtering.
2. Joins & Relationships: Dive into INNER, LEFT, RIGHT joins. Practice combining tables to extract meaningful insights.
3. Aggregations & Functions: Get comfortable with COUNT, SUM, AVG, MAX, GROUP BY, and HAVING clauses. These are essential for summarizing data.
4. Subqueries & Nested Queries: Learn how to query within queries. This is powerful for handling complex datasets.
5. Window Functions: Explore ranking, cumulative sums, and sliding windows to work with running totals and moving averages.
6. Optimization: Study indexing and query optimization for faster, more efficient queries.
7. Real-World Scenarios: Apply your SQL knowledge to solve real-world business problems.
The journey may seem tough, but each step sharpens your skills and brings you closer to data analysis excellence. Stay consistent, practice regularly, and let SQL become your superpower! ๐ช
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
If youโre aiming to become a data analyst, mastering SQL is non-negotiable.
Hereโs a smart roadmap to ace it:
1. Basics First: Understand data types, simple queries (SELECT, FROM, WHERE). Master basic filtering.
2. Joins & Relationships: Dive into INNER, LEFT, RIGHT joins. Practice combining tables to extract meaningful insights.
3. Aggregations & Functions: Get comfortable with COUNT, SUM, AVG, MAX, GROUP BY, and HAVING clauses. These are essential for summarizing data.
4. Subqueries & Nested Queries: Learn how to query within queries. This is powerful for handling complex datasets.
5. Window Functions: Explore ranking, cumulative sums, and sliding windows to work with running totals and moving averages.
6. Optimization: Study indexing and query optimization for faster, more efficient queries.
7. Real-World Scenarios: Apply your SQL knowledge to solve real-world business problems.
The journey may seem tough, but each step sharpens your skills and brings you closer to data analysis excellence. Stay consistent, practice regularly, and let SQL become your superpower! ๐ช
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐6
Essential SQL Topics for Data Analyst
Introduction to Databases
Fundamentals of databases and Database Management Systems (DBMS)
Basic SQL syntax and structure
Retrieving Data
Using the SELECT statement
Filtering data with the WHERE clause
Sorting results using ORDER BY
Limiting output with LIMIT (MySQL) or TOP (SQL Server)
Basic SQL Functions
Utilizing COUNT, SUM, AVG, MIN, and MAX
Data Types
Numeric, character, date, and time data types
Joining Tables
INNER JOIN
LEFT JOIN (or LEFT OUTER JOIN)
RIGHT JOIN (or RIGHT OUTER JOIN)
FULL JOIN (or FULL OUTER JOIN)
CROSS JOIN
Self JOIN
Advanced Data Filtering
Using IN and NOT IN
Applying BETWEEN for range filtering
Using LIKE with wildcards
Handling NULL values with IS NULL and IS NOT NULL
Grouping and Aggregation
GROUP BY clause
Filtering groups with HAVING
Subqueries
Subqueries in the SELECT clause
Subqueries in the WHERE clause
Derived tables using subqueries in the FROM clause
Correlated subqueries
Set Operations
Combining results with UNION
UNION ALL for combining results including duplicates
INTERSECT for common elements
EXCEPT (or MINUS) for differences
Window Functions
Using ROW_NUMBER
RANK and DENSE_RANK
NTILE for distributing rows
LEAD and LAG for accessing prior or subsequent rows
Aggregate functions as window functions (SUM, AVG, COUNT)
Common Table Expressions (CTEs)
Using the WITH clause
Creating recursive CTEs
Stored Procedures and Functions
Creating and utilizing stored procedures
Creating and utilizing user-defined functions
Views
Creating and managing views
Using indexed views (materialized views)
Indexing
Creating indexes
Understanding clustered versus non-clustered indexes
Maintaining indexes
Transactions
Controlling transactions with BEGIN, COMMIT, and ROLLBACK
Performance Optimization
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
Introduction to Databases
Fundamentals of databases and Database Management Systems (DBMS)
Basic SQL syntax and structure
Retrieving Data
Using the SELECT statement
Filtering data with the WHERE clause
Sorting results using ORDER BY
Limiting output with LIMIT (MySQL) or TOP (SQL Server)
Basic SQL Functions
Utilizing COUNT, SUM, AVG, MIN, and MAX
Data Types
Numeric, character, date, and time data types
Joining Tables
INNER JOIN
LEFT JOIN (or LEFT OUTER JOIN)
RIGHT JOIN (or RIGHT OUTER JOIN)
FULL JOIN (or FULL OUTER JOIN)
CROSS JOIN
Self JOIN
Advanced Data Filtering
Using IN and NOT IN
Applying BETWEEN for range filtering
Using LIKE with wildcards
Handling NULL values with IS NULL and IS NOT NULL
Grouping and Aggregation
GROUP BY clause
Filtering groups with HAVING
Subqueries
Subqueries in the SELECT clause
Subqueries in the WHERE clause
Derived tables using subqueries in the FROM clause
Correlated subqueries
Set Operations
Combining results with UNION
UNION ALL for combining results including duplicates
INTERSECT for common elements
EXCEPT (or MINUS) for differences
Window Functions
Using ROW_NUMBER
RANK and DENSE_RANK
NTILE for distributing rows
LEAD and LAG for accessing prior or subsequent rows
Aggregate functions as window functions (SUM, AVG, COUNT)
Common Table Expressions (CTEs)
Using the WITH clause
Creating recursive CTEs
Stored Procedures and Functions
Creating and utilizing stored procedures
Creating and utilizing user-defined functions
Views
Creating and managing views
Using indexed views (materialized views)
Indexing
Creating indexes
Understanding clustered versus non-clustered indexes
Maintaining indexes
Transactions
Controlling transactions with BEGIN, COMMIT, and ROLLBACK
Performance Optimization
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐7โค2
SQL Interview Questions! ๐ฅ๐
Basic SQL Interview Questions:
- What is SQL?
- What are the different types of SQL commands?
- What is the difference between DDL, DML, DCL, and TCL?
- What is the difference between SQL and MySQL?
- What is a primary key?
- What is a foreign key?
- What is a unique key?
- What is the difference between primary key and unique key?
- What is the difference between HAVING and WHERE?
- What are constraints in SQL? Name a few.
- What is the difference between CHAR and VARCHAR?
- What is Normalization? What are its types?
- What is Denormalization?
- What is an index in SQL?
- What are the different types of indexes?
- What is the difference between Clustered and Non-clustered indexes?
- What is an alias in SQL?
- What is the difference between DELETE and TRUNCATE?
- What is the difference between TRUNCATE and DROP?
- What is a view in SQL?
-------------------------------------
Intermediate SQL Interview Questions:
What is a self-join?
What is an inner join?
What is the difference between INNER JOIN and OUTER JOIN?
What are the types of OUTER JOIN?
What is a cross join?
What is a Cartesian join?
What is the difference between UNION and UNION ALL?
What is the difference between JOIN and UNION?
What is a stored procedure?
What is a trigger in SQL?
What are the different types of triggers?
What is the difference between HAVING and GROUP BY?
What are subqueries?
What are correlated subqueries?
What is an EXISTS clause in SQL?
What is the difference between EXISTS and IN?
What is a cursor in SQL?
What is the difference between OLTP and OLAP?
What are ACID properties in SQL?
What is normalization? Explain 1NF, 2NF, 3NF, and BCNF.
What is a composite key?
What is a surrogate key?
What is the use of the COALESCE function?
What is the difference between IS
NULL and IS NOT NULL?
What is partitioning in SQL?
-------------------------------------
Advanced SQL Interview Questions:
What are window functions in SQL?
What is CTE (Common Table Expression)?
What is the difference between TEMP TABLE and CTE?
What is the difference between RANK(), DENSE_RANK(), and ROW_NUMBER()?
What is a materialized view?
What is the difference between materialized views and normal views?
What is sharding in SQL?
What is the MERGE statement?
What is the JSON data type in SQL?
What is recursive CTE?
What is the difference between LEFT JOIN and LEFT OUTER JOIN?
How does indexing impact performance?
What is the difference between OLAP and OLTP?
What is ETL (Extract, Transform, Load)?
What are window functions? Explain LEAD, LAG, and NTILE.
What is a pivot table in SQL?
What is Dynamic SQL?
What is a NoSQL database? How is it different from SQL databases?
What is the difference between SQL and PL/SQL?
How to find the N-th highest salary in SQL?
-------------------------------------
Practical SQL Queries:
Find the second highest salary from an Employee table.
Find duplicate records in a table.
Write a SQL query to find the count of employees in each department.
Write a query to find employees who earn more than their managers.
Write a query to fetch the first three characters of a string.
Write a SQL query to swap two columns in a table without using a temporary table.
Write a query to find all employees who joined in the last 6 months.
Write a query to find the most repeated values in a column.
Write a query to delete duplicate rows from a table.
Write a SQL query to find all customers who made more than 5 purchases.
React โฅ๏ธ for more content like this ๐
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
Basic SQL Interview Questions:
- What is SQL?
- What are the different types of SQL commands?
- What is the difference between DDL, DML, DCL, and TCL?
- What is the difference between SQL and MySQL?
- What is a primary key?
- What is a foreign key?
- What is a unique key?
- What is the difference between primary key and unique key?
- What is the difference between HAVING and WHERE?
- What are constraints in SQL? Name a few.
- What is the difference between CHAR and VARCHAR?
- What is Normalization? What are its types?
- What is Denormalization?
- What is an index in SQL?
- What are the different types of indexes?
- What is the difference between Clustered and Non-clustered indexes?
- What is an alias in SQL?
- What is the difference between DELETE and TRUNCATE?
- What is the difference between TRUNCATE and DROP?
- What is a view in SQL?
-------------------------------------
Intermediate SQL Interview Questions:
What is a self-join?
What is an inner join?
What is the difference between INNER JOIN and OUTER JOIN?
What are the types of OUTER JOIN?
What is a cross join?
What is a Cartesian join?
What is the difference between UNION and UNION ALL?
What is the difference between JOIN and UNION?
What is a stored procedure?
What is a trigger in SQL?
What are the different types of triggers?
What is the difference between HAVING and GROUP BY?
What are subqueries?
What are correlated subqueries?
What is an EXISTS clause in SQL?
What is the difference between EXISTS and IN?
What is a cursor in SQL?
What is the difference between OLTP and OLAP?
What are ACID properties in SQL?
What is normalization? Explain 1NF, 2NF, 3NF, and BCNF.
What is a composite key?
What is a surrogate key?
What is the use of the COALESCE function?
What is the difference between IS
NULL and IS NOT NULL?
What is partitioning in SQL?
-------------------------------------
Advanced SQL Interview Questions:
What are window functions in SQL?
What is CTE (Common Table Expression)?
What is the difference between TEMP TABLE and CTE?
What is the difference between RANK(), DENSE_RANK(), and ROW_NUMBER()?
What is a materialized view?
What is the difference between materialized views and normal views?
What is sharding in SQL?
What is the MERGE statement?
What is the JSON data type in SQL?
What is recursive CTE?
What is the difference between LEFT JOIN and LEFT OUTER JOIN?
How does indexing impact performance?
What is the difference between OLAP and OLTP?
What is ETL (Extract, Transform, Load)?
What are window functions? Explain LEAD, LAG, and NTILE.
What is a pivot table in SQL?
What is Dynamic SQL?
What is a NoSQL database? How is it different from SQL databases?
What is the difference between SQL and PL/SQL?
How to find the N-th highest salary in SQL?
-------------------------------------
Practical SQL Queries:
Find the second highest salary from an Employee table.
Find duplicate records in a table.
Write a SQL query to find the count of employees in each department.
Write a query to find employees who earn more than their managers.
Write a query to fetch the first three characters of a string.
Write a SQL query to swap two columns in a table without using a temporary table.
Write a query to find all employees who joined in the last 6 months.
Write a query to find the most repeated values in a column.
Write a query to delete duplicate rows from a table.
Write a SQL query to find all customers who made more than 5 purchases.
React โฅ๏ธ for more content like this ๐
Here you can find essential SQL Interview Resources๐
https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐11โค1
๐10 intermediate-level SQL interview questions
1. How would you find the nth highest salary in a table?
2. What is the difference between JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN?
3. How would you calculate cumulative sum in SQL?
4. How do you identify duplicate records in a table?
5. Explain the concept of a window function and give examples.
6. How would you retrieve records between two dates in SQL?
7. What is the difference between UNION and UNION ALL?
8. How can you pivot data in SQL?
9. Explain the use of CASE statements in SQL.
10. How do you use common table expressions (CTEs)?
#sql
1. How would you find the nth highest salary in a table?
2. What is the difference between JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN?
3. How would you calculate cumulative sum in SQL?
4. How do you identify duplicate records in a table?
5. Explain the concept of a window function and give examples.
6. How would you retrieve records between two dates in SQL?
7. What is the difference between UNION and UNION ALL?
8. How can you pivot data in SQL?
9. Explain the use of CASE statements in SQL.
10. How do you use common table expressions (CTEs)?
#sql
๐4โค2
Most people learn SQL just enough to pull some data. But if you really understand it, you can analyze massive datasets without touching Excel or Python.
Here are 8 game-changing SQL concepts that will make you a data pro:
๐
1. Stop pulling raw data. Start pulling insights.
The biggest mistake? Running a query that gives you everything and then filtering it later.
Good analysts donโt pull raw data. They shape the data before it even reaches them.
2. โSELECT โ is a rookie move.
Pulling all columns is lazy and slow.
A pro only selects what they need.
โ๏ธ Fewer columns = Faster queries
โ๏ธ Less noise = Clearer insights
The more precise your query, the less time you waste cleaning data.
3. GROUP BY is your best friend.
You donโt need 100,000 rows of transactions. What you need is:
โ๏ธ Sales per region
โ๏ธ Average order size per customer
โ๏ธ Number of signups per month
Grouping turns chaotic data into useful summaries.
4. Joins = Connecting the dots.
Your most important data is split across multiple tables.
Want to know how much each customer spent? You need to join:
โ๏ธ Customer info
โ๏ธ Order history
โ๏ธ Payments
Joins = unlocking hidden insights.
5. Window functions will blow your mind.
They let you:
โ๏ธ Rank customers by total purchases
โ๏ธ Calculate rolling averages
โ๏ธ Compare each row to the overall trend
Itโs like pivot tables, but way more powerful.
6. CTEs will save you from spaghetti SQL.
Instead of writing a 50-line nested query, break it into steps.
CTEs (Common Table Expressions) make your SQL:
โ๏ธ Easier to read
โ๏ธ Easier to debug
โ๏ธ Reusable
Good SQL is clean SQL.
7. Indexes = Speed.
If your queries take forever, your database is probably doing unnecessary work.
Indexes help databases find data faster.
If you work with large datasets, this is a game changer.
SQL isnโt just about pulling data. Itโs about analyzing, transforming, and optimizing it.
Master these 7 concepts, and youโll never look at SQL the same way again.
Join us on WhatsApp: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
Here are 8 game-changing SQL concepts that will make you a data pro:
๐
1. Stop pulling raw data. Start pulling insights.
The biggest mistake? Running a query that gives you everything and then filtering it later.
Good analysts donโt pull raw data. They shape the data before it even reaches them.
2. โSELECT โ is a rookie move.
Pulling all columns is lazy and slow.
A pro only selects what they need.
โ๏ธ Fewer columns = Faster queries
โ๏ธ Less noise = Clearer insights
The more precise your query, the less time you waste cleaning data.
3. GROUP BY is your best friend.
You donโt need 100,000 rows of transactions. What you need is:
โ๏ธ Sales per region
โ๏ธ Average order size per customer
โ๏ธ Number of signups per month
Grouping turns chaotic data into useful summaries.
4. Joins = Connecting the dots.
Your most important data is split across multiple tables.
Want to know how much each customer spent? You need to join:
โ๏ธ Customer info
โ๏ธ Order history
โ๏ธ Payments
Joins = unlocking hidden insights.
5. Window functions will blow your mind.
They let you:
โ๏ธ Rank customers by total purchases
โ๏ธ Calculate rolling averages
โ๏ธ Compare each row to the overall trend
Itโs like pivot tables, but way more powerful.
6. CTEs will save you from spaghetti SQL.
Instead of writing a 50-line nested query, break it into steps.
CTEs (Common Table Expressions) make your SQL:
โ๏ธ Easier to read
โ๏ธ Easier to debug
โ๏ธ Reusable
Good SQL is clean SQL.
7. Indexes = Speed.
If your queries take forever, your database is probably doing unnecessary work.
Indexes help databases find data faster.
If you work with large datasets, this is a game changer.
SQL isnโt just about pulling data. Itโs about analyzing, transforming, and optimizing it.
Master these 7 concepts, and youโll never look at SQL the same way again.
Join us on WhatsApp: https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v
๐4โค1
Preparing for a SQL interview?
Focus on mastering these essential topics:
1. Joins: Get comfortable with inner, left, right, and outer joins.
Knowing when to use what kind of join is important!
2. Window Functions: Understand when to use
ROW_NUMBER, RANK(), DENSE_RANK(), LAG, and LEAD for complex analytical queries.
3. Query Execution Order: Know the sequence from FROM to
ORDER BY. This is crucial for writing efficient, error-free queries.
4. Common Table Expressions (CTEs): Use CTEs to simplify and structure complex queries for better readability.
5. Aggregations & Window Functions: Combine aggregate functions with window functions for in-depth data analysis.
6. Subqueries: Learn how to use subqueries effectively within main SQL statements for complex data manipulations.
7. Handling NULLs: Be adept at managing NULL values to ensure accurate data processing and avoid potential pitfalls.
8. Indexing: Understand how proper indexing can significantly boost query performance.
9. GROUP BY & HAVING: Master grouping data and filtering groups with HAVING to refine your query results.
10. String Manipulation Functions: Get familiar with string functions like CONCAT, SUBSTRING, and REPLACE to handle text data efficiently.
11. Set Operations: Know how to use UNION, INTERSECT, and EXCEPT to combine or compare result sets.
12. Optimizing Queries: Learn techniques to optimize your queries for performance, especially with large datasets.
If we master/ Practice in these topics we can track any SQL interviews..
Like this post if you need more ๐โค๏ธ
Hope it helps :)
Focus on mastering these essential topics:
1. Joins: Get comfortable with inner, left, right, and outer joins.
Knowing when to use what kind of join is important!
2. Window Functions: Understand when to use
ROW_NUMBER, RANK(), DENSE_RANK(), LAG, and LEAD for complex analytical queries.
3. Query Execution Order: Know the sequence from FROM to
ORDER BY. This is crucial for writing efficient, error-free queries.
4. Common Table Expressions (CTEs): Use CTEs to simplify and structure complex queries for better readability.
5. Aggregations & Window Functions: Combine aggregate functions with window functions for in-depth data analysis.
6. Subqueries: Learn how to use subqueries effectively within main SQL statements for complex data manipulations.
7. Handling NULLs: Be adept at managing NULL values to ensure accurate data processing and avoid potential pitfalls.
8. Indexing: Understand how proper indexing can significantly boost query performance.
9. GROUP BY & HAVING: Master grouping data and filtering groups with HAVING to refine your query results.
10. String Manipulation Functions: Get familiar with string functions like CONCAT, SUBSTRING, and REPLACE to handle text data efficiently.
11. Set Operations: Know how to use UNION, INTERSECT, and EXCEPT to combine or compare result sets.
12. Optimizing Queries: Learn techniques to optimize your queries for performance, especially with large datasets.
If we master/ Practice in these topics we can track any SQL interviews..
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐5โค3๐1
Want to build your first AI agent?
Join a live hands-on session by GeeksforGeeks & Salesforce for working professionals
- Build with Agent Builder
- Assign real actions
- Get a free certificate of participation
Registeration link:๐
https://gfgcdn.com/tu/V4t/
Join a live hands-on session by GeeksforGeeks & Salesforce for working professionals
- Build with Agent Builder
- Assign real actions
- Get a free certificate of participation
Registeration link:๐
https://gfgcdn.com/tu/V4t/
The Only SQL You Actually Need For Your First Job DataAnalytics
The Learning Trap:
* Complex subqueries
* Advanced CTEs
* Recursive queries
* 100+ tutorials watched
* 0 practical experience
Reality Check:
75% of daily SQL tasks:
* Basic SELECT, FROM, WHERE
* JOINs
* GROUP BY
* ORDER BY
* Simple aggregations
* ROW_NUMBER
Like for detailed explanation โค๏ธ
#sql
The Learning Trap:
* Complex subqueries
* Advanced CTEs
* Recursive queries
* 100+ tutorials watched
* 0 practical experience
Reality Check:
75% of daily SQL tasks:
* Basic SELECT, FROM, WHERE
* JOINs
* GROUP BY
* ORDER BY
* Simple aggregations
* ROW_NUMBER
Like for detailed explanation โค๏ธ
#sql
โค16๐1
If you want to Excel at using the most used database language in the world, learn these powerful SQL features:
โข Wildcards (%, _) โ Flexible pattern matching
โข Window Functions โ ROW_NUMBER(), RANK(), DENSE_RANK(), LEAD(), LAG()
โข Common Table Expressions (CTEs) โ WITH for better readability
โข Recursive Queries โ Handle hierarchical data
โข STRING Functions โ LEFT(), RIGHT(), LEN(), TRIM(), UPPER(), LOWER()
โข Date Functions โ DATEDIFF(), DATEADD(), FORMAT()
โข Pivot & Unpivot โ Transform row data into columns
โข Aggregate Functions โ SUM(), AVG(), COUNT(), MIN(), MAX()
โข Joins & Self Joins โ Master INNER, LEFT, RIGHT, FULL, SELF JOIN
โข Indexing โ Speed up queries with CREATE INDEX
Like it if you need a complete tutorial on all these topics! ๐โค๏ธ
#sql
โข Wildcards (%, _) โ Flexible pattern matching
โข Window Functions โ ROW_NUMBER(), RANK(), DENSE_RANK(), LEAD(), LAG()
โข Common Table Expressions (CTEs) โ WITH for better readability
โข Recursive Queries โ Handle hierarchical data
โข STRING Functions โ LEFT(), RIGHT(), LEN(), TRIM(), UPPER(), LOWER()
โข Date Functions โ DATEDIFF(), DATEADD(), FORMAT()
โข Pivot & Unpivot โ Transform row data into columns
โข Aggregate Functions โ SUM(), AVG(), COUNT(), MIN(), MAX()
โข Joins & Self Joins โ Master INNER, LEFT, RIGHT, FULL, SELF JOIN
โข Indexing โ Speed up queries with CREATE INDEX
Like it if you need a complete tutorial on all these topics! ๐โค๏ธ
#sql
๐5โค2๐1
๐Here's a breakdown of SQL interview questions covering various topics:
๐บBasic SQL Concepts:
-Differentiate between SQL and NoSQL databases.
-List common data types in SQL.
๐บQuerying:
-Retrieve all records from a table named "Customers."
-Contrast SELECT and SELECT DISTINCT.
-Explain the purpose of the WHERE clause.
๐บJoins:
-Describe types of joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN).
-Retrieve data from two tables using INNER JOIN.
๐บAggregate Functions:
-Define aggregate functions and name a few.
-Calculate average, sum, and count of a column in SQL.
๐บGrouping and Filtering:
-Explain the GROUP BY clause and its use.
-Filter SQL query results using the HAVING clause.
๐บSubqueries:
-Define a subquery and provide an example.
๐บIndexes and Optimization:
-Discuss the importance of indexes in a database.
&Optimize a slow-running SQL query.
๐บNormalization and Data Integrity:
-Define database normalization and its significance.
-Enforce data integrity in a SQL database.
๐บTransactions:
-Define a SQL transaction and its purpose.
-Explain ACID properties in database transactions.
๐บViews and Stored Procedures:
-Define a database view and its use.
-Distinguish a stored procedure from a regular SQL query.
๐บAdvanced SQL:
-Write a recursive SQL query and explain its use.
-Explain window functions in SQL.
โ ๐These questions offer a comprehensive assessment of SQL knowledge, ranging from basics to advanced concepts.
โค๏ธLike if you'd like answers in the next post! ๐
๐บBasic SQL Concepts:
-Differentiate between SQL and NoSQL databases.
-List common data types in SQL.
๐บQuerying:
-Retrieve all records from a table named "Customers."
-Contrast SELECT and SELECT DISTINCT.
-Explain the purpose of the WHERE clause.
๐บJoins:
-Describe types of joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN).
-Retrieve data from two tables using INNER JOIN.
๐บAggregate Functions:
-Define aggregate functions and name a few.
-Calculate average, sum, and count of a column in SQL.
๐บGrouping and Filtering:
-Explain the GROUP BY clause and its use.
-Filter SQL query results using the HAVING clause.
๐บSubqueries:
-Define a subquery and provide an example.
๐บIndexes and Optimization:
-Discuss the importance of indexes in a database.
&Optimize a slow-running SQL query.
๐บNormalization and Data Integrity:
-Define database normalization and its significance.
-Enforce data integrity in a SQL database.
๐บTransactions:
-Define a SQL transaction and its purpose.
-Explain ACID properties in database transactions.
๐บViews and Stored Procedures:
-Define a database view and its use.
-Distinguish a stored procedure from a regular SQL query.
๐บAdvanced SQL:
-Write a recursive SQL query and explain its use.
-Explain window functions in SQL.
โ ๐These questions offer a comprehensive assessment of SQL knowledge, ranging from basics to advanced concepts.
โค๏ธLike if you'd like answers in the next post! ๐
โค5๐2
Here are some tricky๐งฉ SQL interview questions!
1. Find the second-highest salary in a table without using LIMIT or TOP.
2. Write a SQL query to find all employees who earn more than their managers.
3. Find the duplicate rows in a table without using GROUP BY.
4. Write a SQL query to find the top 10% of earners in a table.
5. Find the cumulative sum of a column in a table.
6. Write a SQL query to find all employees who have never taken a leave.
7. Find the difference between the current row and the next row in a table.
8. Write a SQL query to find all departments with more than one employee.
9. Find the maximum value of a column for each group without using GROUP BY.
10. Write a SQL query to find all employees who have taken more than 3 leaves in a month.
These questions are designed to test your SQL skills, including your ability to write efficient queries, think creatively, and solve complex problems.
Here are the answers to these questions:
1. SELECT MAX(salary) FROM table WHERE salary NOT IN (SELECT MAX(salary) FROM table)
2. SELECT e1.* FROM employees e1 JOIN employees e2 ON e1.manager_id = (link unavailable) WHERE e1.salary > e2.salary
3. SELECT * FROM table WHERE rowid IN (SELECT rowid FROM table GROUP BY column HAVING COUNT(*) > 1)
4. SELECT * FROM table WHERE salary > (SELECT PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY salary) FROM table)
5. SELECT column, SUM(column) OVER (ORDER BY rowid) FROM table
6. SELECT * FROM employees WHERE id NOT IN (SELECT employee_id FROM leaves)
7. SELECT *, column - LEAD(column) OVER (ORDER BY rowid) FROM table
8. SELECT department FROM employees GROUP BY department HAVING COUNT(*) > 1
9. SELECT MAX(column) FROM table WHERE column NOT IN (SELECT MAX(column) FROM table GROUP BY group_column)
Here you can find essential SQL Interview Resources๐
https://t.iss.one/mysqldata
Like this post if you need more ๐โค๏ธ
Hope it helps :)
1. Find the second-highest salary in a table without using LIMIT or TOP.
2. Write a SQL query to find all employees who earn more than their managers.
3. Find the duplicate rows in a table without using GROUP BY.
4. Write a SQL query to find the top 10% of earners in a table.
5. Find the cumulative sum of a column in a table.
6. Write a SQL query to find all employees who have never taken a leave.
7. Find the difference between the current row and the next row in a table.
8. Write a SQL query to find all departments with more than one employee.
9. Find the maximum value of a column for each group without using GROUP BY.
10. Write a SQL query to find all employees who have taken more than 3 leaves in a month.
These questions are designed to test your SQL skills, including your ability to write efficient queries, think creatively, and solve complex problems.
Here are the answers to these questions:
1. SELECT MAX(salary) FROM table WHERE salary NOT IN (SELECT MAX(salary) FROM table)
2. SELECT e1.* FROM employees e1 JOIN employees e2 ON e1.manager_id = (link unavailable) WHERE e1.salary > e2.salary
3. SELECT * FROM table WHERE rowid IN (SELECT rowid FROM table GROUP BY column HAVING COUNT(*) > 1)
4. SELECT * FROM table WHERE salary > (SELECT PERCENTILE_CONT(0.9) WITHIN GROUP (ORDER BY salary) FROM table)
5. SELECT column, SUM(column) OVER (ORDER BY rowid) FROM table
6. SELECT * FROM employees WHERE id NOT IN (SELECT employee_id FROM leaves)
7. SELECT *, column - LEAD(column) OVER (ORDER BY rowid) FROM table
8. SELECT department FROM employees GROUP BY department HAVING COUNT(*) > 1
9. SELECT MAX(column) FROM table WHERE column NOT IN (SELECT MAX(column) FROM table GROUP BY group_column)
Here you can find essential SQL Interview Resources๐
https://t.iss.one/mysqldata
Like this post if you need more ๐โค๏ธ
Hope it helps :)
๐4โค2๐1
Roadmap to master SQL:
๐ *Basic SQL Concepts*
โ๐ Understand Databases & Tables
โ๐ Learn SQL Syntax & Structure
โ๐ Learn Data Types in SQL
โ๐ Learn Basic SELECT Queries
โ๐ Learn WHERE Clause for Filtering Data
โ๐ Learn ORDER BY for Sorting Data
๐ *Advanced SQL Queries*
โ๐ Learn JOINs (INNER, LEFT, RIGHT, FULL, SELF)
โ๐ Learn Aggregation Functions (SUM, AVG, COUNT, MIN, MAX)
โ๐ Learn GROUP BY and HAVING Clauses
โ๐ Learn Subqueries (Nested Queries)
โ๐ Learn UNION and INTERSECT
โ๐ Learn LIKE, IN, and BETWEEN Operators
๐ *Advanced Data Manipulation*
โ๐ Learn Data Manipulation (INSERT, UPDATE, DELETE)
โ๐ Learn Data Constraints (PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL)
โ๐ Learn Normalization & Denormalization
โ๐ Learn Transactions & COMMIT/ROLLBACK
๐ *Performance Optimization*
โ๐ Learn Indexing
โ๐ Learn Query Optimization Techniques
โ๐ Learn EXPLAIN Plan
๐ *Common SQL Functions*
โ๐ Learn Date & Time Functions
โ๐ Learn String Functions (CONCAT, SUBSTRING, TRIM, etc.)
โ๐ Learn Mathematical Functions
โ๐ Learn Window Functions (ROW_NUMBER, RANK, PARTITION BY)
๐ *Working with Views and Stored Procedures*
โ๐ Learn Creating and Using Views
โ๐ Learn Creating and Using Stored Procedures
โ๐ Learn Triggers and Functions
๐ *Build Projects*
โ๐ Create Data Analytics Reports using SQL
โ๐ Build a Database from Scratch
โ๐ Work on Data Cleaning and Transformation Projects
๐ โ *Apply for Jobs*
โ๐ Apply for Data Analyst Roles
โ๐ Highlight SQL Skills & Projects in Resume
React โค๏ธ for detailed explanation of each topic
Data Analyst Roadmap: https://t.iss.one/sqlspecialist/1414
Data Analyst Jobs: https://whatsapp.com/channel/0029Vaxjq5a4dTnKNrdeiZ0J
For all resources and cheat sheets, check out our Telegram channel
๐๐
https://t.iss.one/mysqldata
Hope it helps :)
๐ *Basic SQL Concepts*
โ๐ Understand Databases & Tables
โ๐ Learn SQL Syntax & Structure
โ๐ Learn Data Types in SQL
โ๐ Learn Basic SELECT Queries
โ๐ Learn WHERE Clause for Filtering Data
โ๐ Learn ORDER BY for Sorting Data
๐ *Advanced SQL Queries*
โ๐ Learn JOINs (INNER, LEFT, RIGHT, FULL, SELF)
โ๐ Learn Aggregation Functions (SUM, AVG, COUNT, MIN, MAX)
โ๐ Learn GROUP BY and HAVING Clauses
โ๐ Learn Subqueries (Nested Queries)
โ๐ Learn UNION and INTERSECT
โ๐ Learn LIKE, IN, and BETWEEN Operators
๐ *Advanced Data Manipulation*
โ๐ Learn Data Manipulation (INSERT, UPDATE, DELETE)
โ๐ Learn Data Constraints (PRIMARY KEY, FOREIGN KEY, UNIQUE, NOT NULL)
โ๐ Learn Normalization & Denormalization
โ๐ Learn Transactions & COMMIT/ROLLBACK
๐ *Performance Optimization*
โ๐ Learn Indexing
โ๐ Learn Query Optimization Techniques
โ๐ Learn EXPLAIN Plan
๐ *Common SQL Functions*
โ๐ Learn Date & Time Functions
โ๐ Learn String Functions (CONCAT, SUBSTRING, TRIM, etc.)
โ๐ Learn Mathematical Functions
โ๐ Learn Window Functions (ROW_NUMBER, RANK, PARTITION BY)
๐ *Working with Views and Stored Procedures*
โ๐ Learn Creating and Using Views
โ๐ Learn Creating and Using Stored Procedures
โ๐ Learn Triggers and Functions
๐ *Build Projects*
โ๐ Create Data Analytics Reports using SQL
โ๐ Build a Database from Scratch
โ๐ Work on Data Cleaning and Transformation Projects
๐ โ *Apply for Jobs*
โ๐ Apply for Data Analyst Roles
โ๐ Highlight SQL Skills & Projects in Resume
React โค๏ธ for detailed explanation of each topic
Data Analyst Roadmap: https://t.iss.one/sqlspecialist/1414
Data Analyst Jobs: https://whatsapp.com/channel/0029Vaxjq5a4dTnKNrdeiZ0J
For all resources and cheat sheets, check out our Telegram channel
๐๐
https://t.iss.one/mysqldata
Hope it helps :)
โค6๐6
Quick Recap of SQL Concepts
1๏ธโฃ FROM clause: Specifies the tables from which data will be retrieved.
2๏ธโฃ WHERE clause: Filters rows based on specified conditions.
3๏ธโฃ GROUP BY clause: Groups rows that have the same values into summary rows.
4๏ธโฃ HAVING clause: Filters groups based on specified conditions.
5๏ธโฃ SELECT clause: Specifies the columns to be retrieved.
6๏ธโฃ WINDOW functions: Functions that perform calculations across a set of table rows.
7๏ธโฃ AGGREGATE functions: Functions like COUNT, SUM, AVG that perform calculations on a set of values.
8๏ธโฃ UNION / UNION ALL: Combines the result sets of multiple SELECT statements.
9๏ธโฃ ORDER BY clause: Sorts the result set based on specified columns.
๐ LIMIT / OFFSET (or FETCH / OFFSET in some databases): Controls the number of rows returned and starting point for retrieval.
1๏ธโฃ FROM clause: Specifies the tables from which data will be retrieved.
2๏ธโฃ WHERE clause: Filters rows based on specified conditions.
3๏ธโฃ GROUP BY clause: Groups rows that have the same values into summary rows.
4๏ธโฃ HAVING clause: Filters groups based on specified conditions.
5๏ธโฃ SELECT clause: Specifies the columns to be retrieved.
6๏ธโฃ WINDOW functions: Functions that perform calculations across a set of table rows.
7๏ธโฃ AGGREGATE functions: Functions like COUNT, SUM, AVG that perform calculations on a set of values.
8๏ธโฃ UNION / UNION ALL: Combines the result sets of multiple SELECT statements.
9๏ธโฃ ORDER BY clause: Sorts the result set based on specified columns.
๐ LIMIT / OFFSET (or FETCH / OFFSET in some databases): Controls the number of rows returned and starting point for retrieval.
๐4