Question

我的MySQL查询一直没有结果返回，即使我认为它应该，我可能犯了一个愚蠢的错误。所以一个修复将是太棒了。感谢

SELECT SQL_CALC_FOUND_ROWS business_title, CONCAT(School_title, ', ', County, ', ', Town, ', ', Street_title, ', ', Postcode)
FROM `me-datab`.`business_main_location`
    INNER JOIN `business_site`
        ON `business_site`.Find_Me= `business_main_location`.Find_Me
    INNER JOIN `Personal`
        ON `Personal`.Personal_ID = `business_main_location`.Personal_ID
    INNER JOIN `address`
        ON `address`.Address_ID = `business_main_location`.Find_Me

Answer 1

很有可能，您的某个联接没有匹配的值。您可以使用left join代替inner join来返回结果：

SELECT SQL_CALC_FOUND_ROWS business_title, CONCAT(School_title, ', ', County, ', ', Town, ', ', Street_title, ', ', Postcode)
FROM `me-datab`.`business_main_location`
    LEFT JOIN `business_site`
        ON `business_site`.Find_Me= `business_main_location`.Find_Me
    LEFT JOIN `Personal`
        ON `Personal`.Personal_ID = `business_main_location`.Personal_ID
    LEFT JOIN `address`
        ON `address`.Address_ID = `business_main_location`.Find_Me;

一种可能性是join上的Address;它看起来很可疑。

但是，如果您真的需要帮助，请尝试使用示例数据和您的查询设置SQL Fiddle（www.sqlfiddle.com）。

我的MySQL查询不会返回任何结果？

1 个答案: