Postgresql觸發器示例

Question

當一行更新觸發器將更改該行時，我創建了一個觸發器。當我更新一列時，我收到一個錯誤。我該如何解決？

ERROR: stack depth limit exceeded HINT: Increase the configuration parameter "max_stack_depth" (currently 2048kB), after ensuring the platform's stack depth limit is adequate.

CREATE OR REPLACE FUNCTION ynt_call() 
RETURNS TRIGGER AS $$ 
BEGIN 
    IF TG_OP = 'UPDATE' THEN 
     UPDATE ynt.a_test SET date_time = now(); 
    END IF; 
    RETURN NEW; 
END; 
$$ language 'plpgsql'; 
CREATE TRIGGER update_call AFTER UPDATE ON ynt.a_test FOR EACH ROW EXECUTE PROCEDURE ynt_call(); 

Answer 1

，當然你會循環，直到時間的盡頭，因爲你正在更新行時更新一行。您應該使用特殊變量new設置字段date_time，如下所示：

CREATE OR REPLACE FUNCTION ynt_call() 
RETURNS TRIGGER AS $$ 
BEGIN 
    IF TG_OP = 'UPDATE' THEN 
     new.date_time = now(); 
    END IF; 
    RETURN NEW; 
END; 
$$ language 'plpgsql'; 
CREATE TRIGGER update_call AFTER UPDATE ON ynt.a_test FOR EACH ROW EXECUTE  PROCEDURE ynt_call();