小编jpp*_*pp1的帖子

Postgres 8.4 在这里。想象一下来自 Postgres doc 的这个代码片段：

CREATE FUNCTION emp_stamp() RETURNS trigger AS $emp_stamp$
BEGIN
    -- Check that empname and salary are given
    IF NEW.empname IS NULL THEN
        RAISE EXCEPTION 'empname cannot be null';
    END IF;
    IF NEW.salary IS NULL THEN
        RAISE EXCEPTION '% cannot have null salary', NEW.empname;
    END IF;

    -- Who works for us when she must pay for it?
    IF NEW.salary < 0 THEN
        RAISE EXCEPTION '% cannot have a negative salary', NEW.empname;
    END IF;

    -- …