Update trigger

/*EXAMPLE OF A UPDATE FUNCTION WITH TRIGGER PLPGSQL*/

CREATE OR REPLACE FUNCTION update_aumentarpreco ()
    RETURNS TRIGGER
    LANGUAGE PLPGSQL
    AS 
    $BODY$
BEGIN
	IF OLD.ps_availqty = 2 THEN
		RETURN NULL;
	END IF;
		
    IF NEW.ps_availqty = 2 THEN
        NEW.ps_supplycost = OLD.ps_supplycost * 0.10;
        RETURN NEW;
    END IF;
	
    RETURN NEW;
END;
    $BODY$ 

CREATE TRIGGER update_aumentarpreco
    BEFORE UPDATE OF ps_availqty ON partsupp
    FOR EACH ROW
    EXECUTE PROCEDURE update_aumentarpreco ();

/*DROP TRIGGER update_aumentarpreco ON partsupp*/
/*Testing

UPDATE
    partsupp
SET
    ps_availqty = 4
WHERE
    ps_suppkey = 2*/

Similar codes

0 vote173 views1 answer
Postgresql extract hour and minutes from timestamp
SQL
0 vote177 views1 answer
Migration graphql
SQL
0 vote233 views1 answer
Mysql loop through databases and execute query
SQL
0 vote174 views1 answer
Dapper run sql script with parameters
SQL
0 vote175 views1 answer
Sql on-premises
SQL
48 votes272 views3 answers
Psql create database
SQL
0 vote170 views2 answers
How to update the multiple rows in sql
SQL
0 vote157 views1 answer
Complete date is 1 year or not sql server
SQL
0 vote193 views1 answer
Sqlite get date only
SQL
20 votes157 views5 answers
Sql show tables
SQL