使用其他表的列从表中删除

Posted 2023-03-23

【中文标题】使用其他表的列从表中删除

【英文标题】：Delete from table using column of other table

【发布时间】：2021-05-26 11:47:15

【问题描述】：

我创建了一个过程，在该过程中我创建了一个临时表来存储列的值，然后我想使用这些列值来删除其他表中的数据。 如何在 while 循环中执行此操作，或者我可以使用 join 从 AppCoverLetter 中删除行，AppError 哪种方式更好？

    CREATE DEFINER=`root`@`localhost` PROCEDURE `gdpr_delete`(_email_ varchar(128))
BEGIN
DECLARE NumberRecords int;
DECLARE RowCount int ;
-- Create a temporary table, note the IDENTITY
-- column that will be used to loop through
-- the rows of this table
CREATE TABLE GdprDeleteData (AppId INT NOT null);

-- Insert the resultset we want to loop through
-- into the temporary table

INSERT INTO  GdprDeleteData (AppId) SELECT AppId FROM ApplyData.AppFormData where lower(Email) = lower(_email_);
-- Get the number of records in the temporary table
SET NumberRecords = ROW_COUNT();
SET RowCount = 1;
select NumberRecords, RowCount;
-- loop through all records in the temporary table
-- using the WHILE loop construct
start transaction;
    DELETE AppCoverLetter  FROM AppCoverLetter inner JOIN GdprDeleteData ON AppCoverLetter.AppID = GdprDeleteData.AppId;
    DELETE AppError        FROM AppError inner JOIN GdprDeleteData ON AppError.AppID = GdprDeleteData.AppId;
    DELETE AppFormData     FROM AppFormData inner JOIN GdprDeleteData ON AppFormData.AppID = GdprDeleteData.AppId;
    DELETE AppJobData      FROM AppJobData inner JOIN GdprDeleteData ON AppJobData.AppID = GdprDeleteData.AppId;
    DELETE AppTrackingData FROM AppTrackingData inner JOIN GdprDeleteData ON AppTrackingData.AppID = GdprDeleteData.AppId;
    DELETE FlowLog         FROM FlowLog inner JOIN GdprDeleteData ON FlowLog.AppID = GdprDeleteData.AppId;
    DELETE App             FROM App inner JOIN GdprDeleteData ON App.AppID = GdprDeleteData.AppId;
    DELETE AppCoverLetter  FROM AppCoverLetter inner JOIN GdprDeleteData ON AppCoverLetter.AppID = GdprDeleteData.AppId;
    DELETE AppResume       FROM AppResume inner JOIN GdprDeleteData ON AppResume.AppID = GdprDeleteData.AppId;

  commit;
-- drop the temporary table

drop table  GdprDeleteData;
END

【问题讨论】：

你有什么问题？ ..你有一个错误？？显示错误消息..错误的结果更新您的问题添加正确的数据样本和预期的结果

我想知道当前使用连接删除哪种方式更好，或者我应该使用while循环进行操作

【参考方案1】：

您可以避免临时表和循环 在 mysql 中，您可以在单个查询中从两个表中删除，并使用 sunquery 作为临时数据

   DELETE t1, t2
   FROM AppCoverLetter t1
   INNER JOIN (
     SELECT AppId 
     FROM ApplyData.AppFormData 
     where lower(Email) = lower(_email_)
   ) t3 ON t1.AppID = t3.AppId
   INNER JOIN AppError t2 ON t2.AppID = t3.AppId;

或者如果你有更多的桌子

   DELETE t1, t2, tx
   FROM AppCoverLetter t1
   INNER JOIN (
     SELECT AppId 
     FROM ApplyData.AppFormData 
     where lower(Email) = lower(_email_)
   ) t3 ON t1.AppID = t3.AppId
   INNER JOIN AppError t2 ON t2.AppID = t3.AppId
   INNER JOIN table3 tx ON tx.AppID = t3.AppId;

【讨论】：

如果我有超过 2 张桌子怎么办，请检查有问题的编辑@scaisEdge

答案已更新..您只需要删除子句中的表引用和相关连接

它给出了不止一张表@scaisEdge的语法错误

删除了错误的；在第一个加入答案结束时更新..

如果这3个表中有1个没有匹配条件/没有数据@scaisEdge，它不会删除数据