Mysql存储过程Select Column into OUT参数

Question

我有一个类似于这个的存储过程，当我试图保存它时，我得到这个错误:

Undeclared variable: my_column

CREATE PROCEDURE p (OUT column_param VARCHAR(25))
BEGIN
    SELECT my_column INTO coumn_param limit 1;
END;

为什么我不能选择要返回的列？

这里是我在程序中的实际查询:

select latitude into lat, longitude into lon
from cities cc
inner join countries c on cc.country_id = c.country_id
inner join regions r on cc.region_id = r.region_id and c.country_id = r.country_id
left join locations l on cc.city_id = l.city_id
where 
city = coalesce(cty, city) and
country = coalesce(ctry, country) and
region = coalesce(reg, region)
limit 1;

Answer 1

INTO 子句的语法不正确

假设您的查询本身是正确的并且可以正常工作，并且您声明了 lat 和 lon 变量更改这部分

select latitude into lat, longitude into lon

到

SELECT latitude, longitude INTO  lat, lon

这是 SQLFiddle 演示