# Comprehensive SQL Cheat Sheet

## Table of Contents

1. [Database Basics](#database-basics)
2. [SQL Syntax](#sql-syntax)
3. [Data Types](#data-types)
4. [Table Operations](#table-operations)
5. [Querying Data](#querying-data)
6. [Filtering Data](#filtering-data)
7. [Joins](#joins)
8. [Aggregate Functions](#aggregate-functions)
9. [Group By](#group-by)
10. [Subqueries](#subqueries)
11. [Transactions](#transactions)
12. [Indexes](#indexes)
13. [Views](#views)

## Database Basics

### Creating a Database

```sql
CREATE DATABASE dbname;
```

### Using a Database

```sql
USE dbname;
```

### Deleting a Database

```sql
DROP DATABASE dbname;
```

## SQL Syntax

### SELECT Statement

```sql
SELECT column1, column2 FROM table_name;
```

### WHERE Clause

```sql
SELECT * FROM table_name WHERE condition;
```

### ORDER BY Clause

```sql
SELECT * FROM table_name ORDER BY column1 ASC, column2 DESC;
```

### LIMIT Clause

```sql
SELECT * FROM table_name LIMIT 10;
```

## Data Types

### Numeric Types

```sql
INT, FLOAT, DOUBLE, DECIMAL
```

### Character Types

```sql
CHAR, VARCHAR, TEXT
```

### Date and Time Types

```sql
DATE, TIME, DATETIME
```

## Table Operations

### Creating a Table

```sql
CREATE TABLE table_name (
    column1 datatype,
    column2 datatype,
    ...
);
```

### Altering a Table

```sql
ALTER TABLE table_name
ADD column_name datatype;
```

### Dropping a Table

```sql
DROP TABLE table_name;
```

## Querying Data

### Basic SELECT

```sql
SELECT * FROM table_name;
```

### Aliasing Columns

```sql
SELECT column1 AS alias1, column2 AS alias2 FROM table_name;
```

## Filtering Data

### WHERE Clause

```sql
SELECT * FROM table_name WHERE condition;
```

### AND, OR, NOT

```sql
SELECT * FROM table_name WHERE condition1 AND condition2;
```

### IN Clause

```sql
SELECT * FROM table_name WHERE column_name IN (value1, value2);
```

## Joins

### INNER JOIN

```sql
SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column;
```

### LEFT JOIN

```sql
SELECT * FROM table1 LEFT JOIN table2 ON table1.column = table2.column;
```

### RIGHT JOIN

```sql
SELECT * FROM table1 RIGHT JOIN table2 ON table1.column = table2.column;
```

## Aggregate Functions

### COUNT

```sql
SELECT COUNT(column) FROM table_name;
```

### SUM

```sql
SELECT SUM(column) FROM table_name;
```

### AVG

```sql
SELECT AVG(column) FROM table_name;
```

### MIN and MAX

```sql
SELECT MIN(column), MAX(column) FROM table_name;
```

## Group By

```sql
SELECT column1, COUNT(column2) FROM table_name GROUP BY column1;
```

## Subqueries

### Single-Row Subquery

```sql
SELECT column1 FROM table_name WHERE column2 = (SELECT column2 FROM another_table WHERE condition);
```

### Multi-Row Subquery

```sql
SELECT column1 FROM table_name WHERE column2 IN (SELECT column2 FROM another_table WHERE condition);
```

## Transactions

### Begin Transaction

```sql
BEGIN;
```

### Commit Transaction

```sql
COMMIT;
```

### Rollback Transaction

```sql
ROLLBACK;
```

## Indexes

### Creating an Index

```sql
CREATE INDEX index_name ON table_name (column1, column2);
```

### Dropping an Index

```sql
DROP INDEX index_name;
```

## Views

### Creating a View

```sql
CREATE VIEW view_name AS
SELECT column1, column2 FROM table_name WHERE condition;
```

### Updating a View

```sql
CREATE OR REPLACE VIEW view_name AS
SELECT new_column1, new_column2 FROM table_name WHERE condition;
```

### Dropping a View

```sql
DROP VIEW view_name;
```