当我在mySql中创建事件时指定第二个列名时，为什么选择失败？

Question

When creating an event, why do I get Undeclared variable: voteType when I add a second column to the select sql? Is it not possible to specify a second column in the sql statement? What's the right way to do this?

BEGIN

DECLARE c VARCHAR(2);
DECLARE vElm INT(10);
DECLARE vType TINYINT(1);

select distinct(country) into c from votes;

select votedElm into vElm, voteType into vType from votes where country = c;

END

Answer 1

That's because the INTO syntax in your second case is expecting a variable array as the destination. It's seeing vElm, voteType as the array of variables, but since voteType hasn't been declared as one (because it's really one of your columns), you get an exception. Try it this way instead:

select <columns> into <variables> from ...

In your case:

select votedElm, voteType into vElm, vType from votes where country = c;

There are examples in the MySQL reference for INTO.