PostgreSQL Basic Finishing (iii)

1. Trigger

Record a log when an update is in action

DROP FUNCTION IFEXIST log_test (); CREATE OR REPLACE FUNCTIONLog_test ()RETURNS Trigger  as $$    DECLARE    BEGINRAISE NOTICE'TRIGGER LOG TEST'; RETURN NULL; END;    $$ LANGUAGE Plpgsql; CREATE TRIGGERLog_trigger AfterUPDATE  onEmps forEach ROWEXECUTE Procedurelog_test (); UPDATEEmpsSETSalary= 8000.0 WHEREUserid= Ten;

2. View

2.1, the view is a predefined SQL query, so the data in the table changes and the view changes;

2.3, there is no actual physical data in the view, is a logical concept;

    CREATE VIEW  as        SELECT  as  as  Money         from Emps         WHERE >  + ;         SELECT *  from VIEW;

PostgreSQL Basic Finishing (iii)