Basic SQL queries explained in an easy way

SQL Created on March 24, 2025

1. Create Database

Creates a new database.

sql
CREATE DATABASE mydatabase;

2. Use Database

Selects the database for operations.

sql
USE mydatabase;

3. Create Table

Creates a new table with columns.

sql
CREATE TABLE students (id INT PRIMARY KEY, name VARCHAR(50));

4. Insert Data

Adds a new record to the table.

sql
INSERT INTO students (id, name) VALUES (1, 'Rajesh');

5. Select Data

Fetches all data from a table.

sql
SELECT * FROM students;

6. Filter Data

Fetches data based on conditions.

sql
SELECT * FROM students WHERE id = 1;

7. Update Data

Modifies existing data in a table.

sql
UPDATE students SET name = 'Rahul' WHERE id = 1;

8. Delete Data

Removes data from a table.

sql
DELETE FROM students WHERE id = 1;

9. Order Data

Sorts data in ascending or descending order.

sql
SELECT * FROM students ORDER BY name ASC;

10. Count Rows

Counts total rows in a table.

sql
SELECT COUNT(*) FROM students;

11. Unique Values

Fetches distinct values from a column.

sql
SELECT DISTINCT name FROM students;

12. Limit Results

Fetches limited rows from a table.

sql
SELECT * FROM students LIMIT 2;

13. Join Tables

Combines data from two tables.

sql
SELECT students.name, marks.marks FROM students JOIN marks ON students.id = marks.student_id;

14. Group Data

Groups rows by a column.

sql
SELECT name, COUNT(*) FROM students GROUP BY name;

15. Check NULL

Finds rows with missing values.

sql
SELECT * FROM students WHERE name IS NULL;

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