Ultimate SQL Cheat Sheet 2024 (Download PDF): Queries, Commands, Etc.

This ultimate SQL Cheatsheet has been created to help you understand SQL as quickly as possible. It also contains the most commonly used SQL Keywords and commands that you would need. You can read this tutorial or download the SQL Cheat Sheet pdf for offline use. You can also edit PDF online.

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What is a Database?

Before we get started with SQL Cheat Sheet, we need to understand what a database is and why do we need SQL. If you want to learn this offline, you can download the SQL basics cheat sheet at any time.

Data is a collection of facts related to any object. For example: - Your name, number, birthday, phone number, email address, etc. is a collection of facts about you.

Therefore, a database is a systematic collection of small units of information (data). For example: - An organized list of all the students of a school along with their data (Name, Phone Number, Birthday, etc.) is referred to as a database.

What is an RDBMS(Relational Database Management System)?

RDBMS Stands for Relational DataBase Management System and is a collection of tools that allow users to organize, manipulate, and visualize databases. RDMBS follows some standards that allow for the fastest response from a database and make it easier for humans to interact with a database.

Think of an RDBMS as a tool that allows you to play with your data and generate insights or value from the database.

What is SQL(Structured Query Language)?

Now that you understand what a database is and what a DBMS is, let's understand what SQL is.

To recap, a database is a collection of data and an RDBMS is a tool that allows you to interact with your data. Therefore, you would need a "language" to communicate with the database that humans and computers can understand, and that language is known as SQL.

SQL stands for Structured Query Language. As the name suggests, it is a structured language via which you can query the database for performing various tasks such as Storing, Manipulating, and retrieving data from a database.

SQL is the standard language when it comes to communicating with powerful relational databases such as Oracle, Sybase, Microsoft SQL Server, Access, Ingres, etc. Anything related to data in relational databases, such as creating tables, limiting access to data, sorting, filtering, grouping, etc., is achieved using SQL.

In this SQL cheatsheet, we will be learning everything there is to learn about SQL.

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SQL v/s MySQL: Difference Between Both

Most beginners usually get confused between the two terms - SQL and MySQL, and sometimes use the two interchangeably. However, there is a clear and vast difference between the two.

As defined earlier, SQL is a language that allows one to communicate with the database. MySQL, on the other hand, is an RDBMS in which you can type SQL commands to interact with the database.

SQL is the language/protocol that is used by relational database management systems to allow users to manipulate data in the database.

MySQL is a database management system that provides users with an interface to connect with databases. MySQL provides users with the ability to create various databases, tables, stored procedures, and functions in their database servers. SQL is the language that is used to perform powerful operations on the database.

In this SQL Cheat Sheet, we would be looking at both SQL and MySQL, which would help clarify the difference.

What Can SQL do?

SQL is a powerful programming language that allows you to communicate with the database. Almost all companies use databases to store and retrieve data in some form or the other.

Using SQL, you create Databases, and inside a database, you create various TABLES in which you can add all your data. Using SQL, you can:

1. Create / Delete Databases
2. Create / Delete Table(s) in a database
3. SELECT particular data from table(s)
4. INSERT data into tables
5. UPDATE data in tables
6. DELETE data from tables
7. Create Views in the database
8. Execute various aggregate functions

and tons of other cool stuff. So, let's see how we can harness this power.

How to get started with SQL?

To get started with writing SQL on your computer, you would need to install a Database Management Server. The RDBMS would then give you all the necessary tools to interact with your database.

There are various RDBMS that you can use, and it doesn't matter (much) what system you choose as long as it's working for you. Some of the most common RDBMS are:

1. MySQL
2. Oracle
3. Microsoft SQL Server
4. PostgreSQL
5. Heidi SQL

Just install any of the RDBMS that you like from their official website and you should be able to create a database server by simply following their instructions. Once you have a database server ready, you can get access to a Query Editor where you can type all your SQL queries.

Now, let's get started with our cheat sheet and learn some SQL basics and SQL syntax to get the ball rolling.

Working with Tables

To work with SQL, you need to understand that data is organized into tables. One database would contain all the data for a single application (in most cases). A single database would have multiple tables that store values.

For example:- If you have a restaurant management application or implemented E-Delivery solution for smooth operations, you would have a database that contains tables such as:

1. Customers
2. Orders
3. Menu Items
4. Receipts
5. Combox

etc. Each table would contain a specific type of data and various tables could have different types of relations. Using SQL relations, we can combine values from different tables to fetch the data that we require. (More on relations in a later section)

To create a table, we would require two things. Firstly, we would need all the fields that we want to store in a table. Secondly, we want to define the type of data that would enter into a table.

Let's take the restaurant management application's Customers table as an example. We want to store some information about each of our customers such as their name, Phone Number, and Postal Code. Now that we are done with the first step, we need to define the data types of these values.

The name of a customer would be of character data type because we need to store alphabetical characters. Similarly, the phone number would be characters again because we would need to store country code, and special characters such as '+', '()', etc. The postal code would be of type integer because we need to store numbers. Here is how the table would look like:

To identify each customer uniquely, we add an ID to them so that we can use this ID to connect data from various tables. So, the final table structure could look something like this.

To create this table, we would use the CREATE SQL Command followed by the fields as follows:

CREATE TABLE customers(

ID INT NOT NULL,

name varchar(50),

phone varchar(15),

postalCode INT

);

To delete this table, we would use the DROP command as follows:

DROP TABLE customers;

SQL Data Types for Server

To create tables for manipulating data effectively, we need to work with the correct data type. Let's say we want to work with dates, it would be easier to create a column for holding DATE type values instead of storing them as a string and writing logic to manipulate the values.

Every RDBMS is different and each RDBMS might have a different data type for working with certain values. The following sections of this SQL Cheat Sheet contain the various types of MySQL data types.

String Data Types

Numeric Data Types

Note: All the numeric data types may have an extra option: UNSIGNED or ZEROFILL. If you add the UNSIGNED/ZEROFILL option, MySQL disallows negative values for the column.

Date/Time Data Types

CRUD Operations with SQL

Now that we have our table(s) ready, let's see how we can store and retrieve data from the tables in our database. In the following sections of this SQL Basics Cheat Sheet, we would look at the most basic SQL operations.

CRUD is an acronym that stands for Create, Read, Update, and Delete. These are the most fundamental operations that one can perform on any database. For creating any application, these 4 types of operations are crucial. They are:-

1. INSERT (Create)
2. SELECT (Read)
3. UPDATE (Update)
4. DELETE (Delete)

To insert data into any table, we use the INSERT INTO statement. The general syntax for insert is:

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

       VALUES(val1,val2,...);

To insert data into our customer's table, we would use the following statement:

INSERT INTO customers(ID,name,phone,postalCode)

      VALUES(1,'Alice','+123456789',123456);

To read data from a table, we would use the Select statement where we define the columns that we want to fetch. The general syntax is:

SELECT column1,column2,.. FROM table_name;

If we wanted to select the name and phone number of a customer from our table, we would use:

SELECT name, phone FROM customers;

Also, to read all the columns from our table, we can replace the column names with * as follows:

SELECT * FROM customers;

To update specific column(s) of specific row(s), we make use of the Update statement. The general syntax for an update statement is:

UPDATE table_name

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

  WHERE conditions...;

For example, if we wanted to update the phone number of a customer that has an ID of 2, we would write our query as:

UPDATE customers

  SET phone='+2223334445'

  WHEREID=2;

We can update multiple columns by adding them to the SET statement and we can target multiple rows by adding them to the WHERE statement. We will look at WHERE in detail in later sections of this SQL commands cheat sheet.

If we wanted to remove some rows from a table, we would use the delete statement. The general syntax is:

DELETE FROM table_name

    WHERE condition...;

Let's say we want to remove all the customers who live in a particular area. So, we simply delete those rows that have a specific area code:

DELETE FROM customers

    WHERE postalCode=223344;

List of useful SQL Keywords

In the following section of this SQL Server Cheat Sheet, we will have a look at all the commands/keywords that we can use in SQL to work with data, tables, and databases.

Operators in SQL

SQL has various operators that allow you to manipulate and compare multiple values. These are very useful and handy while creating queries.

In a database, different tables store different values and these values are related to each other. To identify each row uniquely, we make use of SQL keys. An SQL key is either a single column (or attribute) or a group of columns that can uniquely identify rows in a table. SQL Keys ensures that there aren't any rows with duplicate values.

However, the most powerful use of keys is to establish relations between multiple tables in a database. To do so, we need to understand Primary Key and Foreign Key. The following sections of this SQL cheatsheet explain both of these concepts.

It is a key that uniquely identifies a single row in a table. For example, in a customer's table, the ID key can be used as a primary key to uniquely identify a single customer. This key can then be used to fetch data from multiple tables that have data related to the customer.

1. There can only be One Primary Key for a Table.
2. Primary Key should be unique for Each Row.
3. Primary key cannot have Null Values.

Typically, the primary key in a table is the ID column and is usually paired with the AUTO_INCREMENT keyword to uniquely identify the row. To mark a column as the primary key, we use the PRIMARY KEY keyword followed by the column/columns that consist of the primary key. For Example: -

CREATE TABLE users (
    id int NOT NULL AUTO_INCREMENT,
    first_name varchar(255) NOT NULL,
    last_name varchar(255) NOT NULL,
    address varchar(255),
    email varchar(255) NOT NULL,
    PRIMARY KEY (id)
);

CREATE TABLE users (
    id int NOT NULL AUTO_INCREMENT,
    first_name varchar(255) NOT NULL,
    last_name varchar(255) NOT NULL,
    address varchar(255),
    email varchar(255) NOT NULL,
    PRIMARY KEY (id)
);

A foreign key is a field in a table that references the PRIMARY KEY of another table. A foreign key is used to link two tables together by establishing a relationship.

The table that contains the foreign key is known as the child table, while the table containing the primary key for the foreign key is known as the parent table.

For example: Let's say we have 3 different tables to manage a restaurant - products, users, and orders. In our products table, we list all our products and in the user's table, we have details of all our users. When a user places an order, we save the data in the orders table. But, instead of saving the complete details of the product and all the information of the user, we save their primary keys in the orders table.

CREATE TABLE orders(
       order_id INT NOT NULL,
       user_id INT,
       product_id int,
       PRIMARY KEY(order_id),
       FOREIGN KEY(user_id) REFERENCES users(id),
       FOREIGN KEY(product_id) REFERENCES products(id)
    );

CREATE TABLE orders(
       order_id INT NOT NULL,
       user_id INT,
       product_id int,
       PRIMARY KEY(order_id),
       FOREIGN KEY(user_id) REFERENCES users(id),
       FOREIGN KEY(product_id) REFERENCES products(id)
    );

Here, we create a primary key for the order ID as it uniquely identifies an order. Also, we create two foreign keys that reference different primary keys.

Once you understand Primary Key and Foreign Key, you can use joins to fetch data by combining multiple tables. Let's take the orders, customers, and products table as an example.

We can join the orders table with customers and products table to get only the information that we require. Let's say we want to see all the orders with the customer's name, product name, and product price as follows:

To do so, we would use join in SQL as follows:

SELECT orders.order_id, products.product_name,customers.customer_name,products.price
FROM orders
INNER JOIN products ON products.product_id = order.product_id
INNER JOIN customers on customers.customer_id = order.customer_id;

SELECT orders.order_id, products.product_name,customers.customer_name,products.price
FROM orders
INNER JOIN products ON products.product_id = order.product_id
INNER JOIN customers on customers.customer_id = order.customer_id;

1. INNER JOIN - Returns any records which have matching values in both tables.
2. LEFT JOIN - Returns all of the records from the first table, along with any matching records from the second table
3. RIGHT JOIN - Returns all of the records from the second table, along with any matching records from the first
4. FULL JOIN - Returns all records from both tables when there is a match

SQL Cheatsheet for SELECT Queries

SELECT userId,name,age,phone,country FROM Users;

SELECT * FROM Users;

SELECT * FROM Users WHERE age>18;

SELECT DISTINCT country from Users;

SELECT COUNT(*) FROM users WHERE age>18;

SELECT * FROM Users ORDER BY userId ASC/DESC;

Note: You can use ASC for Ascending Order or DESC for descending order. If nothing is specified, sorting is done in Ascending order(ASC).

7. Retrieve Limited RowsSELECT * FROM Users WHERE count

SELECT * FROM Users WHERE country=’india’ LIMIT 20;

SELECT * FROM Users ORDER BY userId OFFSET 10 ROWS;

SELECT AVG(age) FROM USERS;

SELECT * FROM Users INNER JOIN Wallets ON Users.walletId = Wallets.walletId;

Note:- We can use any type of join that we want. The condition via which we want to join the tables needs to be specified after the ON keyword.

SELECT us.userId,us.name,wall.walletId,wall.balance
FROM Users AS us
INNER JOIN Wallets AS wall

SELECT us.userId,us.name,wall.walletId,wall.balance
FROM Users AS us
INNER JOIN Wallets AS wall

Note: - We use the AS keyword to give an alias to a table to make our SELECT statement shorter. We can even eliminate the AS keyword in this case and simply write the Alias after the table name.

SQL Cheatsheet for INSERT Queries

INSERT INTO Users VALUES(‘Kanak Infosystems’,’[email protected]’,9876543210);

INSERT INTO Users(userName,email) VALUES(‘Kanak Infosystems’,’[email protected]’);

INSERT INTO User(userName) VALUES
(‘user1’),
(‘user2’);

INSERT INTO User(userName) VALUES
(‘user1’),
(‘user2’);

Note: - We separate each row with a pair of brackets followed by a comma.

SQL Cheatsheet for TABLE Queries

CREATE TABLE Users(
	id INT PRIMARY KEY,
	userName VARCHAR(50),
	age INT DEFAULT 10
     );

CREATE TABLE Users(
	id INT PRIMARY KEY,
	userName VARCHAR(50),
	age INT DEFAULT 10
     );

TRUNCATE TABLE Users;

ALTER TABLE Users ADD COLUMN country VARCHAR(20);

ALTER TABLE Users DROP COLUMN country;

ALTER TABLE Users RENAME TO Customers;

ALTER TABLE Users RENAME userName to name;

SQL Cheat Sheet for UPDATE/DELETE Queries

UPDATE Users SET country=’india’;

UPDATE Users SET isEligible=’true’ WHERE age>=18;

DELETE FROM Users;

DELETE FROM Users WHERE age<18;

SQL Cheat Sheet for SELECT Filters

SELECT * FROM Users WHERE age>=18 AND country=’india’;

SELECT * FROM Users WHERE country=’india’ OR name LIKE ‘Kan%’;

SELECT * FROM Users WHERE age IN (15,18,22,27);

SELECT * FROM Users WHERE age BETWEEN 25 AND 30

SQL is a definite requirement when you are trying to build an application of any size and scale. Learning SQL might be tough for beginners, but once you get the hang of it, it's just like thinking.

Make sure to bookmark this page and download the SQL cheat sheet pdf if you are working with SQL. If you can remember a particular operation or keyword, you can open up this SQL commands cheat sheet to get all the required information.