SQL, or Structured Query Language, is a programming language used to communicate with databases. With SQL, you can retrieve data from a database, insert new data, and update or delete existing data. You can even modify the structure of a database: you can add or delete tables or columns and change the relationships between tables.

If you’re interested in learning more about SQL but have no prior knowledge of programming or databases, take a look at our SQL Basics course.

SQL is a standard, meaning it is a reference. Read about the history of the SQL standard in our article “The History of SQL Standards.”

In practice, each database system uses its own version of SQL, usually called an SQL dialect. SQL dialects are like dialects in the linguistics sense; they are mutually comprehensible. You don’t need to know every SQL dialect; their differences are very slight.