PostgreSQL

CREATE TABLE COMPANY(
   ID INT PRIMARY KEY     NOT NULL,
   NAME           TEXT    NOT NULL,
   AGE            INT     NOT NULL,
   ADDRESS        CHAR(50),
   SALARY         REAL
);
SELECT ID, NAME, SALARY FROM COMPANY;
SELECT * FROM COMPANY WHERE AGE >= 25 OR SALARY >= 65000;
SELECT * FROM COMPANY WHERE AGE::text LIKE '2%';

PostgreSQL Triggers are database callback functions, which are automatically performed/invoked when a specified database event occurs.

The following are important points about PostgreSQL triggers −

• PostgreSQL trigger can be specified to fire

  • Before the operation is attempted on a row (before constraints are checked and the INSERT, UPDATE or DELETE is attempted)

Links

• https://www.tutorialspoint.com/postgresql/postgresql_overview.htm