之後，如果在

Question

列

空值，我創建一個觸發器這樣

CREATE TRIGGER trigger_academictermregistration AFTER UPDATE ON academictermregistration FOR EACH ROW 
BEGIN 
    DECLARE summary TEXT(65535); 
    SET summary = ''; 
    IF(NEW.version <> OLD.version) THEN 
     SET summary = concat(summary, ' @VER: ', OLD.version, '-->', NEW.version); 
    END IF; 
    IF(NEW.isDeleted <> OLD.isDeleted) THEN 
     SET summary = concat(summary, ' @IS_DELETED: ', OLD.isDeleted, '-->', NEW.isDeleted); 
    END IF; 

    INSERT INTO auditinfo (entityId, entityName, importance, details, modifiedOn, modifiedBy) 
     VALUE (NEW.id, 'AcademicTermRegistration', 1, summary, NOW(), NEW.modifiedBy); 

    IF(NEW.id <> OLD.id) THEN 
     INSERT INTO auditinfo (entityId, entityName, importance, details, timestamp, user_id) 
     VALUE (OLD.id, 'AcademicTermRegistration', 5, concat('ID: ', OLD.id, '-->', NEW.id), NOW(), 'backend'); 
    END IF; 
END 

更新觸發器沒有相應工作，我有一個這樣的觸發器，這是更新表後，但如果跟蹤的列值所做的更改任何值爲空（表示爲isDeleted），然後將該值更新爲非空。審計信息表中沒有細節

Answer 1

從參考 - CONCAT()如果任何參數爲NULL，則返回NULL。

使用COALESCE函數，例如， -

SET summary = CONCAT(summary, ' @IS_DELETED: ', COALESCE(OLD.isDeleted, 'NULL'), '-->', COALESCE(NEW.isDeleted, 'NULL')); 

此外，您還可以使用CONCAT_WS()功能，它分隔爭吵後跳過任何NULL值 -

SET summary = CONCAT_WS('', summary, ' @IS_DELETED: ', OLD.isDeleted, '-->', NEW.isDeleted);