T-SQL 和 WHERE LIKE %Parameter% 子句
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T-SQL and the WHERE LIKE %Parameter% clause
提问by dp3
I was trying to write a statement which uses the WHERE LIKE '%text%' clause, but I am not receiving results when I try to use a parameter for the text. For example, this works:
我试图编写一个使用 WHERE LIKE '%text%' 子句的语句，但是当我尝试为文本使用参数时没有收到结果。例如，这有效：
SELECT Employee WHERE LastName LIKE '%ning%'
This would return users Flenning, Manning, Ningle, etc. But this statement would not:
这将返回用户 Flenning、Manning、Ningle 等。但此语句不会：
DECLARE @LastName varchar(max)
SET @LastName = 'ning'
SELECT Employee WHERE LastName LIKE '%@LastName%'
No results found. Any suggestions? Thanks in advance.
未找到结果。有什么建议？提前致谢。
回答by Mahmoud Gamal
It should be:
它应该是：
...
WHERE LastName LIKE '%' + @LastName + '%';
Instead of:
代替：
...
WHERE LastName LIKE '%@LastName%'
回答by swe
The correct answer is, that, because the '%'-sign is part of your search expression, it should be part of your VALUE, so whereever you SET @LastName(be it from a programming language or from TSQL) you should set it to '%' + [userinput] + '%'
正确答案是，因为'%'-sign 是您搜索表达式的一部分，所以它应该是您的 VALUE 的一部分，所以无论您@LastName在哪里设置（无论是来自编程语言还是来自 TSQL），您都应该将其设置为'%' + [userinput] + '%'
or, in your example:
或者，在您的示例中：
DECLARE @LastName varchar(max)
SET @LastName = 'ning'
SELECT Employee WHERE LastName LIKE '%' + @LastName + '%'
回答by Ramgy Borja
you may try this one, used CONCAT
你可以试试这个，用过CONCAT
WHERE LastName LIKE Concat('%',@LastName,'%')
