MySql触发concat新关键字 [英] MySql trigger concat new keyword

问题描述

我目前在使用concat函数将NEW关键字与列名连接时遇到问题。

I am currently facing an issue in concatenating "NEW" Keyword with column names using concat function..

 SET @values =
(SELECT GROUP_CONCAT(CONCAT_WS('.','new', table1.col) SEPARATOR ',')
FROM tbale1, table2, table3, table4
WHERE table3.table3_id = '001'
AND table3.id = table4.table3_id
AND table4.col = table2.col
AND table1.id = table2.table1_id
ORDER BY table2.col);

执行时，而不是替换NEW关键字的值（最后插入记录/值）它只返回NEW.col1，NEW.col2，NEW.col3而不是它们指定的值。请帮我解决这个问题..



期望的输出是SELECT @var ='aa'，'bb'，'cc'，'ccc';但是当前输出是SELECT @var = NEW.col1，NEW.col2，NEW.col3，NEW.col4;

ON execution, instead of replacing the values for NEW keyword(last inserted records/values) it just returns as NEW.col1,NEW.col2,NEW.col3 instead of their assigned values.please help me out with this..

desired output is SELECT @var ='aa','bb','cc','ccc'; But current output is SELECT @var = NEW.col1,NEW.col2,NEW.col3,NEW.col4;

推荐答案

看起来你正在尝试创建一个动态SQL语句。

在MySQL中，这称为准备语句，你可以在这里查阅参考手册：

13.5准备语句的SQL语法 [ ^ ]

有时MySQL文档不提供最容易理解的例子，所以这里有另一个链接： MySQL准备语句 [ ^ ]



我希望这可以帮助你。

It looks like you are trying to create a SQL statement dynamically.
In MySQL this is called Prepared Statements and you can look up the reference manual here:
13.5 SQL Syntax for Prepared Statements[^]
Sometimes the MySQL documentation doesn't provide the easiest to understand examples, so here is another link: MySQL Prepared Statement[^]

I hope this helps you on the way.

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