example of trigger in postgresql
-- Trigger to update donatiom count in donor table whenever
-- A new donation is made by that person
CREATE or REPLACE FUNCTION increase_count()
RETURNS TRIGGER
AS
$$
BEGIN
UPDATE donor SET dcount = dcount + 1 WHERE did = NEW.did;
END
$$
LANGUAGE plpgsql;
CREATE TRIGGER update_donation_count AFTER INSERT ON donation
FOR EACH ROW
EXECUTE PROCEDURE increase_count();how to drop a trigger in postgresql
DROP TRIGGER [IF EXISTS] trigger-name
ON table-name [ CASCADE | RESTRICT ];mysql create trigger
CREATE
TRIGGER `event_name` BEFORE/AFTER INSERT/UPDATE/DELETE
ON `database`.`table`
FOR EACH ROW BEGIN
-- trigger body
-- this code is applied to every
-- inserted/updated/deleted row
END;
CREATE
TRIGGER `blog_after_insert` AFTER INSERT
ON `blog`
FOR EACH ROW BEGIN
IF NEW.deleted THEN
SET @changetype = 'DELETE';
ELSE
SET @changetype = 'NEW';
END IF;
INSERT INTO audit (blog_id, changetype) VALUES (NEW.id, @changetype);
END$$mssql trigger
-- SQL Server Syntax
-- Trigger on an INSERT, UPDATE, or DELETE statement to a table or view (DML Trigger)
CREATE [ OR ALTER ] TRIGGER [ schema_name . ]trigger_name
ON { table | view }
[ WITH <dml_trigger_option> [ ,...n ] ]
{ FOR | AFTER | INSTEAD OF }
{ [ INSERT ] [ , ] [ UPDATE ] [ , ] [ DELETE ] }
[ WITH APPEND ]
[ NOT FOR REPLICATION ]
AS { sql_statement [ ; ] [ ,...n ] | EXTERNAL NAME <method specifier [ ; ] > }
<dml_trigger_option> ::=
[ ENCRYPTION ]
[ EXECUTE AS Clause ]
<method_specifier> ::=
assembly_name.class_name.method_nameCopyright © 2021 Codeinu
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