Added SQL sheet.

README.md

@@ -11,6 +11,7 @@
 - [Perl](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/perl.md)
 - [PHP](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/PHP.md)
 - [Python](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/python.md)
+- [SQL](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/SQL.md)
 ### Guides
 - [LEMP Guide](https://git.namenode.xyz/CSnap/cheetsheetz/src/branch/main/LEMP.md)
 

SQL.md

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+# 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;
+```
+
+