Creating a database structure

After the database is created, the following three SQL statements will allow you to create and change the database structure. This is done through database entities, such as a table, function, or constraint:

• The CREATE statement creates the database entity
• The ALTER statement changes the database entity
• The DROP statement deletes the database entity

There are also various SQL statements that allow you to inquire about each database entity. Such statements are database-specific and, typically, they are only used in a database console. For example, in the PostgreSQL console, \d <table> can be used to describe a table, while \dt lists all the tables. Refer to your database documentation for more details.

To create a table, you can execute the following SQL statement:

CREATE TABLE tablename ( column1 type1, column2 type2, ... ); 

The limitations...