本文介绍了MySQL DECLARE 中的 SELECT INTO 变量导致语法错误?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
我想将单个值 SELECT 到一个变量中.我试图遵循:
I´d like to SELECT a single value into a variable. I´d tried to following:
DECLARE myvar INT(4);
-- 立即返回一些语法错误.
-- immediately returns some syntax error.
SELECT myvalue
FROM mytable
WHERE anothervalue = 1;
-- 返回一个整数
SELECT myvalue
INTO myvar
FROM mytable
WHERE anothervalue = 1;
-- 不行，也试过@myvar
-- does not work, also tried @myvar
是否可以在存储过程或函数之外使用 DECLARE?
Is possible to use DECLARE outside of stored procedures or functions?
也许我只是不明白用户变量的概念......我只是试过:
Maybe I just dont get the concept of user variables... I just tried:
SELECT myvalue INTO @var FROM `mytable` WHERE uid = 1;
SELECT @var;
...就像它应该的那样工作.但是如果我一次运行每个查询，我只会得到@var NULL.
...which worked just like it´s supposed to. But if I run each query at a time i just get @var NULL.
推荐答案
最后一个存储过程解决了我的问题.
In the end a stored procedure was the solution for my problem.
这里有什么帮助:
DELIMITER //
CREATE PROCEDURE test ()
BEGIN
DECLARE myvar DOUBLE;
SELECT somevalue INTO myvar FROM mytable WHERE uid = 1;
SELECT myvar;
END//
DELIMITER ;
call test();
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