Sign in
Programming·

SQL Cheat Sheet

A quick reference for SQL,covers the fundamental aspects of SQL. You can expand on these basics as needed for more advanced SQL functionality.

Basics

Creating a Database:

CREATE DATABASE database_name;

Using a Database:

USE database_name;

Creating a Table:

CREATE TABLE table_name (
    column1 datatype constraints,
    column2 datatype constraints,
    ...
);

Dropping a Table:

DROP TABLE table_name;

Data Types

Numeric:

  • INT
  • FLOAT
  • DECIMAL

String:

  • CHAR(size)
  • VARCHAR(size)
  • TEXT

Date and Time:

  • DATE
  • TIME
  • DATETIME
  • TIMESTAMP

CRUD Operations

Inserting Data:

INSERT INTO table_name (column1, column2, ...)
VALUES (value1, value2, ...);

Selecting Data:

SELECT column1, column2, ...
FROM table_name
WHERE condition
ORDER BY column ASC|DESC
LIMIT number;

Updating Data:

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

Deleting Data:

DELETE FROM table_name
WHERE condition;

Constraints

Primary Key:

CREATE TABLE table_name (
    column_name datatype PRIMARY KEY
);

Foreign Key:

CREATE TABLE table_name (
    column_name datatype,
    FOREIGN KEY (column_name) REFERENCES other_table(column_name)
);

Unique:

CREATE TABLE table_name (
    column_name datatype UNIQUE
);

Not Null:

CREATE TABLE table_name (
    column_name datatype NOT NULL
);

Check:

CREATE TABLE table_name (
    column_name datatype,
    CHECK (condition)
);

Default:

CREATE TABLE table_name (
    column_name datatype DEFAULT default_value
);

Joins

Inner Join:

SELECT columns
FROM table1
INNER JOIN table2
ON table1.column = table2.column;

Left Join:

SELECT columns
FROM table1
LEFT JOIN table2
ON table1.column = table2.column;

Right Join:

SELECT columns
FROM table1
RIGHT JOIN table2
ON table1.column = table2.column;

Full Outer Join:

SELECT columns
FROM table1
FULL OUTER JOIN table2
ON table1.column = table2.column;

Aggregation

Count:

SELECT COUNT(column_name)
FROM table_name
WHERE condition;

Sum:

SELECT SUM(column_name)
FROM table_name
WHERE condition;

Average:

SELECT AVG(column_name)
FROM table_name
WHERE condition;

Max:

SELECT MAX(column_name)
FROM table_name
WHERE condition;

Min:

SELECT MIN(column_name)
FROM table_name
WHERE condition;

Group By and Having

Group By:

SELECT column_name, aggregate_function(column_name)
FROM table_name
WHERE condition
GROUP BY column_name;

Having:

SELECT column_name, aggregate_function(column_name)
FROM table_name
GROUP BY column_name
HAVING condition;

Indexes

Creating an Index:

CREATE INDEX index_name
ON table_name (column_name);

Dropping an Index:

DROP INDEX index_name
ON table_name;