Using SQLite

Data Definition Language

The DDL is used to define the structure of data containers and objects within the database. The most common of these containers and objects are tables, indexes, and views. As you’ll see, most objects are defined with a variation of the CREATE command, such as CREATE TABLE or CREATE VIEW. The DROP command is used to delete an existing object (and all of the data it might contain). Examples include DROP TABLE or DROP INDEX. Because the command syntax is so different, statements like CREATE TABLE or CREATE INDEX are usually considered to be separate commands, and not variations of a single CREATE command.

In a sense, the DDL commands are similar to C/C++ header files. DDL commands are used to define the structure, names, and types of the data containers within a database, just as a header file typically defines type definitions, structures, classes, and other data structures. DDL commands are typically used to set up and configure a brand new database before data is entered.

Note

DDL commands define the basic structure of the database and are typically run when a new database is created.

DDL commands are often held in a script file, so that the structure of the database can be easily recreated. Sometimes, especially during development, you may need to recreate only part of the database. To help support this, most CREATE commands in SQLite have an optional IF NOT EXISTS clause.

Normally, a CREATE statement will return an error if an object with the requested name ...