SQL Commands Cheat Sheet

This cheat sheet provides an extensive list of SQL commands and their descriptions. The commands are divided into different categories for easy reference.

Data Definition Language (DDL)

DDL commands are used to define the database schema and create, modify, and delete database objects.

Command	Description
CREATE DATABASE	Creates a new database
CREATE TABLE	Creates a new table
ALTER TABLE	Modifies an existing table
DROP TABLE	Deletes a table
CREATE INDEX	Creates an index on a table
DROP INDEX	Deletes an index from a table

Data Manipulation Language (DML)

DML commands are used to manipulate data in the database.

Command	Description
SELECT	Retrieves data from one or more tables
INSERT INTO	Inserts new data into a table
UPDATE	Modifies existing data in a table
DELETE FROM	Deletes data from a table

Data Control Language (DCL)

DCL commands are used to control access to the database.

Command	Description
GRANT	Grants privileges to a user or role
REVOKE	Revokes privileges from a user or role

Transaction Control Language (TCL)

TCL commands are used to manage transactions in the database.

Command	Description
COMMIT	Commits a transaction
ROLLBACK	Rolls back a transaction
SAVEPOINT	Creates a savepoint within a transaction
ROLLBACK TO SAVEPOINT	Rolls back to a savepoint within a transaction

Aggregate Functions

Aggregate functions are used to perform calculations on a set of values and return a single value.

Function	Description
AVG	Calculates the average value
COUNT	Counts the number of values
MAX	Returns the maximum value
MIN	Returns the minimum value
SUM	Calculates the sum of values

String Functions

String functions are used to manipulate string values.

Function	Description
CONCAT	Concatenates two or more strings
LENGTH	Returns the length of a string
LOWER	Converts a string to lowercase
UPPER	Converts a string to uppercase
SUBSTRING	Returns a substring of a string

Date Functions

Date functions are used to manipulate date and time values.

Function	Description
CURRENT_DATE	Returns the current date
CURRENT_TIME	Returns the current time
CURRENT_TIMESTAMP	Returns the current timestamp
DATEADD	Adds a specified interval to a date
DATEDIFF	Returns the difference between two dates

Joins

Joins are used to combine data from two or more tables.

Join	Description
INNER JOIN	Returns only the rows that have matching values in both tables
LEFT JOIN	Returns all the rows from the left table and the matching rows from the right table
RIGHT JOIN	Returns all the rows from the right table and the matching rows from the left table
FULL OUTER JOIN	Returns all the rows from both tables, with NULL values in the columns where there is no match

Subqueries

Subqueries are used to retrieve data from one table based on the values in another table.

Subquery	Description
IN	Returns rows where the value matches any value in a subquery
EXISTS	Returns rows where a subquery returns at least one row
NOT EXISTS	Returns rows where a subquery returns no rows

References

• MySQL Documentation
• PostgreSQL Documentation
• Oracle Documentation
• Microsoft SQL Server Documentation