PostgreSQL触发器不会插入审计值

Question

我正在使用PostgreSQL 8.1，并且我为表创建了一个触发器，所以如果有事情被更新或插入，它也会在日志表中注册，但我遇到了问题与NULL值：

如果我更新一个NULL值的列，那么它不会插入任何值的日志，但与字符char将罚款，所以也许我失去了一些东西。

CREATE FUNCTION "public"."log_test_trigger"() RETURNS "trigger" AS 'BEGIN 
... 
    IF (TG_OP = ''UPDATE'') THEN 
      IF (NEW.name <> OLD.name) THEN 
        INSERT INTO log_test (type, table, field, old_val, new_val, user, event) VALUES (NEW.type, TG_RELNAME, ''name'', OLD.name, NEW.name, NEW.user, ''UPDATE''); 
      END IF; 
... 
END;' LANGUAGE "plpgsql" 
VOLATILE 
CALLED ON NULL INPUT 
SECURITY INVOKER 

任何帮助：

CREATE TABLE log_test(

    id_test   integer NOT NULL DEFAULT nextval('id_test_seq'), 
    type   char(3), 
    product   char(10), 
    table    char(15), 
    field   char(10), 
    old_val   char(10), 
    new_val   char(10), 
    user   char(10), 
    event   char(10), 
    date   timestamp with time zone  NOT NULL DEFAULT now(), 
CONSTRAINT "log_test_prim" PRIMARY KEY ("id_test") 
); 

触发当时想创建：

该表是这样产生的？

Answer 1

您无法将NULL与某个值进行比较，即NULL = 2和NULL <> 2均为NULL。添加ISNULL：

... 
IF (TG_OP = ''UPDATE'') THEN 
    IF (NEW.name <> OLD.name OR NEW.name ISNULL) THEN 
     INSERT INTO log_test (type, table, field, old_val, new_val, user, event) VALUES (NEW.type, TG_RELNAME, ''name'', OLD.name, NEW.name, NEW.user, ''UPDATE''); 
    END IF; 
... 

或（可能更好）coalesce()两个NEW和OLD记录：

... 
IF (TG_OP = ''UPDATE'') THEN 
    IF (coalesce(NEW.name, '') <> coalesce(OLD.name, '')) THEN 
     INSERT INTO log_test (type, table, field, old_val, new_val, user, event) VALUES (NEW.type, TG_RELNAME, ''name'', OLD.name, NEW.name, NEW.user, ''UPDATE''); 
    END IF; 
...