MySql SELECT INTO变量:返回null [英] MySql SELECT INTO Variable: returns null

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:

1. SELECT @var1:=columnname1, @var2:=columnname2 FROM tbname WHERE menuname='somevalue':这正在工作
2. 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

1. SELECT @var1:=columnname1, @var2:=columnname2 FROM tbname WHERE menuname='somevalue': this is working
2. SELECT 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

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