pgsql触发器函数

-- Function: maint_sales_summary_bytime()

-- DROP FUNCTION maint_sales_summary_bytime();

CREATE OR REPLACE FUNCTION maint_sales_summary_bytime()
  RETURNS trigger AS
$BODY$
    DECLARE
        delta_time_key          integer;
        delta_amount_sold       numeric(15,2);
        delta_units_sold        numeric(12);
        delta_amount_cost       numeric(15,2);
    BEGIN

        -- Work out the increment/decrement amount(s).
        IF (TG_OP = 'DELETE') THEN

            delta_time_key = OLD.time_key;
            delta_amount_sold = -1 * OLD.amount_sold;
            delta_units_sold = -1 * OLD.units_sold;
            delta_amount_cost = -1 * OLD.amount_cost;

        ELSIF (TG_OP = 'UPDATE') THEN

            -- forbid updates that change the time_key -
            -- (probably not too onerous, as DELETE + INSERT is how most
            -- changes will be made).
            IF ( OLD.time_key != NEW.time_key) THEN
                RAISE EXCEPTION 'Update of time_key : % -> %
 not allowed', OLD.time_key, NEW.time_key;
            END IF;

            delta_time_key = OLD.time_key;
            delta_amount_sold = NEW.amount_sold -
 OLD.amount_sold;
            delta_units_sold = NEW.units_sold - OLD.units_sold;
            delta_amount_cost = NEW.amount_cost -
 OLD.amount_cost;

        ELSIF (TG_OP = 'INSERT') THEN

            delta_time_key = NEW.time_key;
            delta_amount_sold = NEW.amount_sold;
            delta_units_sold = NEW.units_sold;
            delta_amount_cost = NEW.amount_cost;

        END IF;

        -- Insert or update the summary row with the new values.
        <>
        LOOP
            UPDATE sales_summary_bytime
                SET amount_sold = amount_sold +
 delta_amount_sold,
                    units_sold = units_sold + delta_units_sold,
                    amount_cost = amount_cost + delta_amount_cost
                WHERE time_key = delta_time_key;

            EXIT insert_update WHEN found;

            BEGIN
                INSERT INTO sales_summary_bytime (
                            time_key,
                            amount_sold,
                            units_sold,
                            amount_cost)
                    VALUES (
                            delta_time_key,
                            delta_amount_sold,
                            delta_units_sold,
                            delta_amount_cost
                           );

                EXIT insert_update;

            EXCEPTION
                WHEN UNIQUE_VIOLATION THEN
                    -- do nothing
            END;
        END LOOP insert_update;

        RETURN NULL;

    END;
$BODY$
  LANGUAGE 'plpgsql' VOLATILE
  COST 100;
ALTER FUNCTION maint_sales_summary_bytime() OWNER TO postgres;

 

------------------------------------------------------------------------------------------

 

-- Function: process_emp_audit()

-- DROP FUNCTION process_emp_audit();

CREATE OR REPLACE FUNCTION process_emp_audit()
  RETURNS trigger AS
$BODY$
    BEGIN
        --
        -- Create a row in emp_audit to reflect the
        -- operation performed on emp, make use of the
        -- special variable TG_OP to work out the
        -- operation.
        --
        IF (TG_OP = 'DELETE') THEN
            INSERT INTO emp_audit SELECT 'D', now(), user, OLD.*;
            RETURN OLD;
        ELSIF (TG_OP = 'UPDATE') THEN
            INSERT INTO emp_audit SELECT 'U', now(), user, NEW.*;
            RETURN NEW;
        ELSIF (TG_OP = 'INSERT') THEN
            INSERT INTO emp_audit SELECT 'I', now(), user, NEW.*;
            RETURN NEW;
        END IF;
        RETURN NULL; -- result is ignored since this is an AFTER trigger

    END;
$BODY$
  LANGUAGE 'plpgsql' VOLATILE
  COST 100;
ALTER FUNCTION process_emp_audit() OWNER TO postgres;
GRANT EXECUTE ON FUNCTION process_emp_audit() TO postgres;

--------------------------------------函数---------------------------------------

-- Function: proc_check_max(character, character)

-- DROP FUNCTION proc_check_max(character, character);

CREATE OR REPLACE FUNCTION proc_check_max(v_tno character, v_cno character)
  RETURNS integer AS
$BODY$
DECLARE
    a_max integer;
    a_cur integer;
BEGIN
    LOCK TABLE 教师选课结果表 IN EXCLUSIVE MODE;
    SELECT 人数上限 INTO a_max FROM 上课地点表;
    SELECT 选课人数 INTO a_cur FROM 教师选课结果表
 WHERE 教师号 IS NOT NULL and 选课号 IS NOT NULL ;
    IF a_max < ( a_cur + 1 ) THEN
         RETURN 0 ;
--RAISE EXCEPTION '超过最大人数限制,无法报名';
    ELSE
        RETURN 1 ;
    END IF;
END;
$BODY$
  LANGUAGE 'plpgsql' VOLATILE
  COST 100;
ALTER FUNCTION proc_check_max(character, character) OWNER TO postgres;