本文介绍了MySql SELECT INTO变量:返回null的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在通过以下两种方式使用select进入变量查询:
I am using a select into variable query in two ways as follows:
-
SELECT @var1:=columnname1, @var2:=columnname2 FROM tbname WHERE menuname='somevalue'
:这正在工作 -
SELECT columnname1,columnname2 INTO @var1,@var2 FROM tbname WHERE menuname='somevalue'
:这并非在所有情况下都有效有时返回空值
SELECT @var1:=columnname1, @var2:=columnname2 FROM tbname WHERE menuname='somevalue'
: this is workingSELECT columnname1,columnname2 INTO @var1,@var2 FROM tbname WHERE menuname='somevalue'
: this is not working in all cases Returns null sometimes
请任何人指导我为什么(2)查询仅在某些时候起作用,这是更合适的方式.当我针对(2)中的where条件运行查询(1)时,它给了我结果.
Please can anyone guide me why the (2) query works only sometimes and which is the more appropriate way. While when I run query (1) for the same where condition as in (2), it gives me results.
推荐答案
我通过使用以下查询(2)解决了我的问题
I resolved my problem by using the following for query (2)
SELECT columnname1,columnname2 INTO @var1,@var2 FROM tbname WHERE menuname='somevalue' limit 1; SELECT @var1;
现在返回变量2的值.我错过了select @var1
声明
which now returns me the value of variable2. I was missing the select @var1
statement
感谢您的帮助
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