PL/SQL 为什么我在触发操作时出现 DEADLOCK？

Question

我有以下触发器

    CREATE OR REPLACE TRIGGER LAST_EDIT 
    BEFORE UPDATE ON MESSAGES
    FOR EACH ROW
    DECLARE
    pragma autonomous_transaction;
    BEGIN
     if :NEW.TEXT <> :OLD.TEXT THEN
      UPDATE MESSAGES set MESSAGES.LAST_EDITED=(select USERS.EMAIL from USERS inner join LAST_EDITED_TABLE on users.ID=LAST_EDITED_TABLE.USER_ID  where 
      LAST_EDITED_TABLE.MESSAGE_ID=(select MESSAGE_ID from LAST_EDITED_TABLE where DATE_MESSAGE=(select max(DATE_MESSAGE) from LAST_EDITED_TABLE )));
    ENDIF;
COMMIT;
END;

然后出现以下错误

ORA-06512: at "DIP.MESSAGEPACKAGE", line 35
00060. 00000 -  "deadlock detected while waiting for resource"
*Cause:    Transactions deadlocked one another while waiting for resources.
*Action:   Look at the trace file to see the transactions and resources
           involved. Retry if necessary

我正在尝试更新表明谁进行了最后一次更新的行（同一 table 中的一行）。谁能帮帮我？

Answer 1

这不是你真正需要的吗？

CREATE OR REPLACE TRIGGER LAST_EDIT 
BEFORE UPDATE ON MESSAGES
FOR EACH ROW
DECLARE
  email USERS.EMAIL%type;
BEGIN     
 if :NEW.TEXT <> :OLD.TEXT THEN
  select USERS.EMAIL into email 
    from USERS inner join LAST_EDITED_TABLE on users.ID=LAST_EDITED_TABLE.USER_ID  
     where LAST_EDITED_TABLE.MESSAGE_ID = (select MESSAGE_ID from LAST_EDITED_TABLE where DATE_MESSAGE = (select max(DATE_MESSAGE) from LAST_EDITED_TABLE ));
  :NEW.LAST_EDITED = email;
END IF;
COMMIT;
END;
/

查找电子邮件的查询逻辑也太复杂了。当然你可以简化它。

PL/SQL 为什么我在触发操作时出现 DEADLOCK？

PL/SQL Why I get DEADLOCK on trigger action?

deadlock

plsql

database-connection

dml

database-trigger