SQL Query Library

SQL Query Examples

Find the SQL query you need with practical examples for common use cases. Each query includes explanations, variants, and pro tips.

120

Query Examples

15+

Use Cases

3

Database Flavors

Popular SQL Queries

How to Calculate Date Difference in SQL

Calculate the difference between two dates in days, months, or years.

How to Compare Current Row with Previous in SQL

Access previous or next row values using LAG and LEAD window functions.

How to Concatenate Strings in SQL

Combine multiple strings or columns into one using CONCAT or || operator.

How to Count Rows in SQL

Count the total number of rows in a table using COUNT() or COUNT(column).

How to Count Rows in SQL in SQL

Count the total number of rows in a table using COUNT() or COUNT(column).

How to Delete Duplicate Rows in SQL

Remove duplicate records while keeping one copy using CTEs and ROW_NUMBER.

How to Filter NULL Values in SQL

Handle NULL values using IS NULL, IS NOT NULL, and COALESCE.

How to Find Duplicate Records in SQL

Identify duplicate rows in a table using GROUP BY and HAVING.

How to Get Second Highest Value in SQL

Find the second highest salary or value using subquery or LIMIT OFFSET.

How to Join Two Tables in SQL

Combine data from multiple tables using INNER JOIN, LEFT JOIN, or RIGHT JOIN.

How to Rank Rows in SQL

Assign rankings using ROW_NUMBER, RANK, or DENSE_RANK window functions.

How to Select Top N Rows in SQL

Retrieve the first N rows from a result set using LIMIT, TOP, or FETCH.

Aggregation

→ How to Count Rows in SQL → How to Count Rows in SQL in SQL → How to SQL Query with GROUP BY and Aggregates in SQL → MySQL: How to Count Rows in SQL → MySQL: How to Count Rows in SQL in SQL → MySQL: How to SQL Query with GROUP BY and Aggregates in SQL → MySQL: SQL Query with GROUP BY and Aggregates → PostgreSQL: How to Count Rows in SQL → PostgreSQL: How to Count Rows in SQL in SQL → PostgreSQL: How to SQL Query with GROUP BY and Aggregates in SQL → PostgreSQL: SQL Query with GROUP BY and Aggregates → SQL Query with GROUP BY and Aggregates → SQL Server: How to Count Rows in SQL → SQL Server: How to Count Rows in SQL in SQL → SQL Server: How to SQL Query with GROUP BY and Aggregates in SQL → SQL Server: SQL Query with GROUP BY and Aggregates

Data Quality

→ How to Delete Duplicate Rows in SQL → How to Filter NULL Values in SQL → How to Find Duplicate Records in SQL → MySQL: How to Delete Duplicate Rows in SQL → MySQL: How to Filter NULL Values in SQL → MySQL: How to Find Duplicate Records in SQL → MySQL: SQL Query to Delete Duplicate Rows → MySQL: SQL Query to Filter NULL Values → MySQL: SQL Query to Find Duplicate Records → PostgreSQL: How to Delete Duplicate Rows in SQL → PostgreSQL: How to Filter NULL Values in SQL → PostgreSQL: How to Find Duplicate Records in SQL → PostgreSQL: SQL Query to Delete Duplicate Rows → PostgreSQL: SQL Query to Filter NULL Values → PostgreSQL: SQL Query to Find Duplicate Records → SQL Query to Delete Duplicate Rows → SQL Query to Filter NULL Values → SQL Query to Find Duplicate Records → SQL Server: How to Delete Duplicate Rows in SQL → SQL Server: How to Filter NULL Values in SQL → SQL Server: How to Find Duplicate Records in SQL → SQL Server: SQL Query to Delete Duplicate Rows → SQL Server: SQL Query to Filter NULL Values → SQL Server: SQL Query to Find Duplicate Records

Joins

→ How to Join Two Tables in SQL → MySQL: How to Join Two Tables in SQL → MySQL: SQL Query to Join Two Tables → PostgreSQL: How to Join Two Tables in SQL → PostgreSQL: SQL Query to Join Two Tables → SQL Query to Join Two Tables → SQL Server: How to Join Two Tables in SQL → SQL Server: SQL Query to Join Two Tables

Ranking

→ How to Get Second Highest Value in SQL → How to Rank Rows in SQL → How to Select Top N Rows in SQL → MySQL: How to Get Second Highest Value in SQL → MySQL: How to Rank Rows in SQL → MySQL: How to Select Top N Rows in SQL → MySQL: SQL Query to Get Second Highest Value → MySQL: SQL Query to Rank Rows → MySQL: SQL Query to Select Top N Rows → PostgreSQL: How to Get Second Highest Value in SQL → PostgreSQL: How to Rank Rows in SQL → PostgreSQL: How to Select Top N Rows in SQL → PostgreSQL: SQL Query to Get Second Highest Value → PostgreSQL: SQL Query to Rank Rows → PostgreSQL: SQL Query to Select Top N Rows → SQL Query to Get Second Highest Value → SQL Query to Rank Rows → SQL Query to Select Top N Rows → SQL Server: How to Get Second Highest Value in SQL → SQL Server: How to Rank Rows in SQL → SQL Server: How to Select Top N Rows in SQL → SQL Server: SQL Query to Get Second Highest Value → SQL Server: SQL Query to Rank Rows → SQL Server: SQL Query to Select Top N Rows

Window Functions

→ How to Rank Rows in SQL → How to SQL Query for Running Total in SQL → MySQL: How to Rank Rows in SQL → MySQL: How to SQL Query for Running Total in SQL → MySQL: SQL Query for Running Total → MySQL: SQL Query to Rank Rows → PostgreSQL: How to Rank Rows in SQL → PostgreSQL: How to SQL Query for Running Total in SQL → PostgreSQL: SQL Query for Running Total → PostgreSQL: SQL Query to Rank Rows → SQL Query for Running Total → SQL Query to Rank Rows → SQL Server: How to Rank Rows in SQL → SQL Server: How to SQL Query for Running Total in SQL → SQL Server: SQL Query for Running Total → SQL Server: SQL Query to Rank Rows

Other

→ How to Calculate Date Difference in SQL → How to Compare Current Row with Previous in SQL → How to Concatenate Strings in SQL → How to SQL CASE WHEN Statement Examples in SQL → How to SQL Pivot Table Query in SQL → MySQL: How to Calculate Date Difference in SQL → MySQL: How to Compare Current Row with Previous in SQL → MySQL: How to Concatenate Strings in SQL → MySQL: How to SQL CASE WHEN Statement Examples in SQL → MySQL: How to SQL Pivot Table Query in SQL → MySQL: SQL CASE WHEN Statement Examples → MySQL: SQL Pivot Table Query → MySQL: SQL Query to Calculate Date Difference → MySQL: SQL Query to Compare Current Row with Previous → MySQL: SQL Query to Concatenate Strings → PostgreSQL: How to Calculate Date Difference in SQL → PostgreSQL: How to Compare Current Row with Previous in SQL → PostgreSQL: How to Concatenate Strings in SQL → PostgreSQL: How to SQL CASE WHEN Statement Examples in SQL → PostgreSQL: How to SQL Pivot Table Query in SQL → PostgreSQL: SQL CASE WHEN Statement Examples → PostgreSQL: SQL Pivot Table Query → PostgreSQL: SQL Query to Calculate Date Difference → PostgreSQL: SQL Query to Compare Current Row with Previous → PostgreSQL: SQL Query to Concatenate Strings → SQL CASE WHEN Statement Examples → SQL Pivot Table Query → SQL Query to Calculate Date Difference → SQL Query to Compare Current Row with Previous → SQL Query to Concatenate Strings → SQL Server: How to Calculate Date Difference in SQL → SQL Server: How to Compare Current Row with Previous in SQL → SQL Server: How to Concatenate Strings in SQL → SQL Server: How to SQL CASE WHEN Statement Examples in SQL → SQL Server: How to SQL Pivot Table Query in SQL → SQL Server: SQL CASE WHEN Statement Examples → SQL Server: SQL Pivot Table Query → SQL Server: SQL Query to Calculate Date Difference → SQL Server: SQL Query to Compare Current Row with Previous → SQL Server: SQL Query to Concatenate Strings

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