Home » SQL Tutorial

SQL Tutorial

8 hours Beginner 1M+ learners

SQL is a standard language for storing, manipulating and retrieving data in databases.

Our SQL tutorial will teach you how to use SQL in: MySQL, SQL Server, MS Access, Oracle, Sybase, Informix, Postgres, and other database systems.

Example

SELECT * FROM Customers;

What is SQL?

  • SQL stands for Structured Query Language
  • SQL lets you access and manipulate databases
  • SQL became a standard of the American National Standards Institute (ANSI) in 1986
  • SQL became a standard of the International Organization for Standardization (ISO) in 1987

What Can SQL do?

  • SQL can execute queries against a database
  • SQL can retrieve data from a database
  • SQL can insert records in a database
  • SQL can update records in a database
  • SQL can delete records from a database
  • SQL can create new databases
  • SQL can create new tables in a database
  • SQL can create stored procedures in a database
  • SQL can create views in a database
  • SQL can set permissions on tables, procedures, and views
Tip: SQL is a standard language, but there are different versions of the SQL language. However, to be compliant with the ANSI standard, they all support at least the major commands (such as SELECT, UPDATE, DELETE, INSERT, WHERE) in a similar manner.

RDBMS

RDBMS stands for Relational Database Management System.

RDBMS is the basis for SQL, and for all modern database systems such as MS SQL Server, IBM DB2, Oracle, MySQL, and Microsoft Access.

The data in RDBMS is stored in database objects called tables. A table is a collection of related data entries and it consists of columns and rows.

Example - Customers Table

CustomerID CustomerName ContactName Country
1 Alfreds Futterkiste Maria Anders Germany
2 Ana Trujillo Ana Trujillo Mexico
3 Antonio Moreno Antonio Moreno Mexico

Every table is broken up into smaller entities called fields. The fields in the Customers table consist of CustomerID, CustomerName, ContactName, and Country. A field is a column in a table that is designed to maintain specific information about every record in the table.

A record, also called a row, is each individual entry that exists in a table.

Database Tables

A database most often contains one or more tables. Each table is identified by a name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.

Note: Throughout this tutorial we will use the well-known Northwind sample database (included in MS Access and MS SQL Server).

Keep in Mind That...

  • SQL keywords are NOT case sensitive: select is the same as SELECT
  • Some database systems require a semicolon at the end of each SQL statement
  • Semicolon is the standard way to separate each SQL statement in database systems that allow more than one SQL statement to be executed in the same call to the server

Try SQL Yourself

In this tutorial we will use our online SQL editor to demonstrate the different SQL statements.

Test Yourself With Exercises

Exercise:

Insert the missing statement to get all the columns from the Customers table.

* FROM Customers;
Next