Learning PostgreSQL 11 - Third Edition

SQL lexical structure

The minimum SQL instruction that can be executed by the database engine is a statement. It can also be called a command or query. For example, each of the following is a statement:

SELECT car_id, number_of_doors FROM car_portal_app.car;DELETE FROM car_portal_app.a;SELECT now();

SQL commands are terminated by a semicolon, ;.

The end of input also terminates a command, but that depends on the tools being used; for example, psql would not execute a command when the user presses Enter if there is no semicolon, it would just move to a new line. However, when psql executes a SQL script from a file, the last command is always executed, even without a semicolon.

The following elements form the lexical structure of SQL:

• Keywords ...