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https://github.com/mergisi/sql-syntax-cheat-sheet

A comprehensive SQL syntax cheat sheet for quick reference, covering essential commands, functions, operators, and concepts across various database systems.
https://github.com/mergisi/sql-syntax-cheat-sheet

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A comprehensive SQL syntax cheat sheet for quick reference, covering essential commands, functions, operators, and concepts across various database systems.

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README 

          
Certainly! Creating a SQL Syntax Cheat Sheet is a great idea to help others learn and reference SQL commands quickly. Below is a comprehensive cheat sheet formatted in Markdown, suitable for a GitHub repository.



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# SQL Syntax Cheat Sheet



A quick reference guide to SQL syntax, commands, and functions.



---



## Table of Contents



1. [Data Definition Language (DDL)](#1-data-definition-language-ddl)

   - [CREATE](#create)

   - [ALTER](#alter)

   - [DROP](#drop)

2. [Data Manipulation Language (DML)](#2-data-manipulation-language-dml)

   - [SELECT](#select)

   - [INSERT](#insert)

   - [UPDATE](#update)

   - [DELETE](#delete)

3. [Data Control Language (DCL)](#3-data-control-language-dcl)

   - [GRANT](#grant)

   - [REVOKE](#revoke)

4. [Transaction Control Language (TCL)](#4-transaction-control-language-tcl)

   - [COMMIT](#commit)

   - [ROLLBACK](#rollback)

   - [SAVEPOINT](#savepoint)

5. [Constraints](#5-constraints)

6. [Operators](#6-operators)

7. [Functions](#7-functions)

   - [Aggregate Functions](#aggregate-functions)

   - [String Functions](#string-functions)

   - [Date and Time Functions](#date-and-time-functions)

8. [Joins](#8-joins)

   - [INNER JOIN](#inner-join)

   - [LEFT JOIN](#left-join)

   - [RIGHT JOIN](#right-join)

   - [FULL OUTER JOIN](#full-outer-join)

9. [Subqueries](#9-subqueries)

10. [Views](#10-views)

11. [Indexes](#11-indexes)

12. [Stored Procedures and Functions](#12-stored-procedures-and-functions)

13. [Common Clauses](#13-common-clauses)

    - [WHERE](#where)

    - [GROUP BY](#group-by)

    - [HAVING](#having)

    - [ORDER BY](#order-by)

    - [LIMIT / TOP / FETCH](#limit--top--fetch)

14. [Data Types](#14-data-types)

15. [Additional Resources](#15-additional-resources)



---



## 1. Data Definition Language (DDL)



### CREATE



**Create a Database**



```sql

CREATE DATABASE database_name;

```



**Create a Table**



```sql

CREATE TABLE table_name (

    column1 datatype [constraints],

    column2 datatype [constraints],

    ...

);

```



*Example:*



```sql

CREATE TABLE Customers (

    CustomerID INT PRIMARY KEY,

    FirstName VARCHAR(50) NOT NULL,

    LastName VARCHAR(50) NOT NULL,

    Email VARCHAR(100) UNIQUE,

    CreatedDate DATE DEFAULT CURRENT_DATE

);

```



### ALTER



**Add a Column**



```sql

ALTER TABLE table_name

ADD column_name datatype [constraints];

```



**Modify a Column**



```sql

ALTER TABLE table_name

MODIFY COLUMN column_name new_datatype;

```



**Drop a Column**



```sql

ALTER TABLE table_name

DROP COLUMN column_name;

```



### DROP



**Drop a Table**



```sql

DROP TABLE table_name;

```



**Drop a Database**



```sql

DROP DATABASE database_name;

```



---



## 2. Data Manipulation Language (DML)



### SELECT



**Basic Syntax**



```sql

SELECT column1, column2, ...

FROM table_name

[WHERE condition]

[GROUP BY column1, column2, ...]

[HAVING condition]

[ORDER BY column1 [ASC|DESC], column2 [ASC|DESC], ...];

```



*Example:*



```sql

SELECT FirstName, LastName

FROM Customers

WHERE CreatedDate > '2023-01-01'

ORDER BY LastName ASC;

```



### INSERT



**Insert Into All Columns**



```sql

INSERT INTO table_name

VALUES (value1, value2, ...);

```



**Insert Into Specific Columns**



```sql

INSERT INTO table_name (column1, column2, ...)

VALUES (value1, value2, ...);

```



*Example:*



```sql

INSERT INTO Customers (FirstName, LastName, Email)

VALUES ('Alice', 'Smith', 'alice@example.com');

```



### UPDATE



```sql

UPDATE table_name

SET column1 = value1, column2 = value2, ...

WHERE condition;

```



*Example:*



```sql

UPDATE Customers

SET Email = 'newemail@example.com'

WHERE CustomerID = 1;

```



### DELETE



```sql

DELETE FROM table_name

WHERE condition;

```



*Example:*



```sql

DELETE FROM Customers

WHERE CustomerID = 1;

```



---



## 3. Data Control Language (DCL)



### GRANT



```sql

GRANT privilege_type ON object_name TO user [WITH GRANT OPTION];

```



*Example:*



```sql

GRANT SELECT, INSERT ON Customers TO 'db_user';

```



### REVOKE



```sql

REVOKE privilege_type ON object_name FROM user;

```



*Example:*



```sql

REVOKE INSERT ON Customers FROM 'db_user';

```



---



## 4. Transaction Control Language (TCL)



### COMMIT



```sql

COMMIT;

```



### ROLLBACK



```sql

ROLLBACK;

```



### SAVEPOINT



```sql

SAVEPOINT savepoint_name;

```



**Rollback to Savepoint**



```sql

ROLLBACK TO SAVEPOINT savepoint_name;

```



---



## 5. Constraints



- **NOT NULL**: Ensures a column cannot have a NULL value.

- **UNIQUE**: Ensures all values in a column are unique.

- **PRIMARY KEY**: Uniquely identifies each record in a table.

- **FOREIGN KEY**: Ensures referential integrity between tables.

- **CHECK**: Ensures that all values in a column satisfy a specific condition.

- **DEFAULT**: Sets a default value for a column if none is specified.



*Example:*



```sql

CREATE TABLE Orders (

    OrderID INT PRIMARY KEY,

    OrderDate DATE NOT NULL,

    CustomerID INT,

    FOREIGN KEY (CustomerID) REFERENCES Customers(CustomerID)

);

```



---



## 6. Operators



- **Arithmetic Operators**: `+`, `-`, `*`, `/`, `%`

- **Comparison Operators**: `=`, `<>` or `!=`, `>`, `<`, `>=`, `<=`

- **Logical Operators**: `AND`, `OR`, `NOT`

- **Other Operators**: `BETWEEN`, `IN`, `LIKE`, `IS NULL`, `EXISTS`



*Example:*



```sql

SELECT * FROM Products

WHERE Price BETWEEN 10 AND 50;



SELECT * FROM Customers

WHERE Email LIKE '%@example.com';

```



---



## 7. Functions



### Aggregate Functions



- **COUNT()**: Counts the number of rows.

- **SUM()**: Calculates the sum of a numeric column.

- **AVG()**: Calculates the average value.

- **MIN()**: Finds the minimum value.

- **MAX()**: Finds the maximum value.



*Example:*



```sql

SELECT COUNT(*) FROM Orders;



SELECT CustomerID, SUM(TotalAmount) as TotalSpent

FROM Orders

GROUP BY CustomerID;

```



### String Functions



- **UPPER(string)**: Converts to uppercase.

- **LOWER(string)**: Converts to lowercase.

- **SUBSTRING(string, start, length)**: Extracts a substring.

- **TRIM(string)**: Removes whitespace.

- **CONCAT(string1, string2, ...)**: Concatenates strings.



*Example:*



```sql

SELECT UPPER(FirstName), LOWER(LastName)

FROM Customers;

```



### Date and Time Functions



- **NOW()**: Returns current date and time.

- **CURDATE()**: Returns current date.

- **DATE_ADD(date, INTERVAL value unit)**: Adds a time interval to a date.

- **DATEDIFF(date1, date2)**: Returns the difference between two dates.



*Example:*



```sql

SELECT NOW();



SELECT DATE_ADD(CURDATE(), INTERVAL 7 DAY);

```



---



## 8. Joins



### INNER JOIN



Returns records with matching values in both tables.



```sql

SELECT columns

FROM table1

INNER JOIN table2 ON table1.column = table2.column;

```



*Example:*



```sql

SELECT Orders.OrderID, Customers.FirstName, Customers.LastName

FROM Orders

INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;

```



### LEFT JOIN



Returns all records from the left table, and matched records from the right table.



```sql

SELECT columns

FROM table1

LEFT JOIN table2 ON table1.column = table2.column;

```



### RIGHT JOIN



Returns all records from the right table, and matched records from the left table.



```sql

SELECT columns

FROM table1

RIGHT JOIN table2 ON table1.column = table2.column;

```



### FULL OUTER JOIN



Returns all records when there is a match in either left or right table.



```sql

SELECT columns

FROM table1

FULL OUTER JOIN table2 ON table1.column = table2.column;

```



---



## 9. Subqueries



A query nested inside another query.



```sql

SELECT column1

FROM table1

WHERE column2 = (SELECT column FROM table2 WHERE condition);

```



*Example:*



```sql

SELECT FirstName, LastName

FROM Customers

WHERE CustomerID IN (SELECT CustomerID FROM Orders WHERE TotalAmount > 1000);

```



---



## 10. Views



A virtual table based on the result set of an SQL statement.



**Create a View**



```sql

CREATE VIEW view_name AS

SELECT columns

FROM table

WHERE condition;

```



*Example:*



```sql

CREATE VIEW HighValueOrders AS

SELECT OrderID, CustomerID, TotalAmount

FROM Orders

WHERE TotalAmount > 1000;

```



---



## 11. Indexes



Used to speed up the retrieval of data.



**Create an Index**



```sql

CREATE INDEX index_name

ON table_name (column1, column2, ...);

```



**Create a Unique Index**



```sql

CREATE UNIQUE INDEX index_name

ON table_name (column);

```



---



## 12. Stored Procedures and Functions



### Stored Procedure



A set of SQL statements that can be stored and executed on the database server.



**Create a Stored Procedure**



```sql

CREATE PROCEDURE procedure_name (parameters)

BEGIN

    -- SQL statements

END;

```



*Example:*



```sql

CREATE PROCEDURE GetCustomerOrders(IN custID INT)

BEGIN

    SELECT * FROM Orders WHERE CustomerID = custID;

END;

```



### User-Defined Function



A function that returns a single value.



**Create a Function**



```sql

CREATE FUNCTION function_name (parameters)

RETURNS datatype

BEGIN

    DECLARE variable datatype;

    -- SQL statements

    RETURN variable;

END;

```



---



## 13. Common Clauses



### WHERE



Filters records that meet specific conditions.



```sql

SELECT * FROM table_name

WHERE condition;

```



### GROUP BY



Groups rows that have the same values in specified columns.



```sql

SELECT column1, AGG_FUNC(column2)

FROM table_name

GROUP BY column1;

```



### HAVING



Filters groups according to specified conditions.



```sql

SELECT column1, AGG_FUNC(column2)

FROM table_name

GROUP BY column1

HAVING condition;

```



### ORDER BY



Sorts the result set.



```sql

SELECT * FROM table_name

ORDER BY column1 [ASC|DESC], column2 [ASC|DESC];

```



### LIMIT / TOP / FETCH



Limits the number of records returned.



- **MySQL, PostgreSQL, SQLite**



  ```sql

  SELECT * FROM table_name

  LIMIT number OFFSET offset;

  ```



- **SQL Server**



  ```sql

  SELECT TOP number * FROM table_name;

  ```



- **Oracle**



  ```sql

  SELECT * FROM table_name

  FETCH FIRST number ROWS ONLY;

  ```



---



## 14. Data Types



### Numeric



- `INT`

- `DECIMAL(p, s)`

- `FLOAT`

- `DOUBLE`



### String



- `CHAR(n)`

- `VARCHAR(n)`

- `TEXT`



### Date and Time



- `DATE`

- `TIME`

- `DATETIME`

- `TIMESTAMP`



### Binary



- `BINARY`

- `VARBINARY`

- `BLOB`



### Boolean



- `BOOLEAN` or `BIT`



---



## 15. Additional Resources



- **Official Documentation**

  - [MySQL Documentation](https://dev.mysql.com/doc/)

  - [PostgreSQL Documentation](https://www.postgresql.org/docs/)

  - [SQL Server Documentation](https://docs.microsoft.com/en-us/sql/sql-server/)

  - [SQLite Documentation](https://www.sqlite.org/docs.html)

- **Online Tutorials**

  - [W3Schools SQL Tutorial](https://www.w3schools.com/sql/)

  - [TutorialsPoint SQL Tutorial](https://www.tutorialspoint.com/sql/index.htm)

- **Practice Platforms**

  - [SQLBolt](https://sqlbolt.com/)

  - [HackerRank SQL Challenges](https://www.hackerrank.com/domains/sql)

  - [LeetCode Database Problems](https://leetcode.com/problemset/database/)



### AI-Powered Tools



- **[AI2sql](https://www.ai2sql.io/)**: Generate SQL queries from natural language descriptions using AI.



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## How to Use This Cheat Sheet



- **Learning**: Use this guide as a starting point to learn SQL syntax and concepts.

- **Reference**: Quickly look up syntax for SQL commands and functions.

- **Contribution**: Feel free to contribute by suggesting improvements or adding new sections.



## License



This cheat sheet is released under the [MIT License](LICENSE).



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**Note:** SQL syntax may vary slightly between different database systems (e.g., MySQL, PostgreSQL, SQL Server, Oracle). Always refer to the official documentation of the database you are using for exact syntax and additional features.



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