改进可怕的多子查询 SQL

Posted 2023-04-15

【中文标题】改进可怕的多子查询 SQL

【英文标题】：Improve horrible, multiple-sub-query SQL

【发布时间】：2012-01-27 00:20:34

【问题描述】：

您将如何改进以下产品 i18n 检索 SQL 以不使用子查询？

SELECT
 l.code,
 l.rtl,
 l.name,
 (SELECT title FROM product_i18n WHERE product_id = :product_id AND culture = l.code) AS title,
 (SELECT description FROM product_i18n WHERE product_id = :product_id AND culture = l.code) AS description,
 (SELECT keywords FROM product_i18n WHERE product_id = :product_id AND culture = l.code) AS keywords
FROM
 language AS l
WHERE
 l.status = 1
ORDER BY
 IFNULL(l.sort, l.id)

【参考方案1】：

类似

SELECT
 l.code,
 l.rtl,
 l.name,
 p.title,
 p.description,
 p.keywords
From
 language AS l
inner join product_il8n p on p.culture = l.code and p.product_id = :product_id
WHERE
 l.status = 1
ORDER BY
 IFNULL(l.sort, l.id)

【讨论】：

是 on 子句中不必要的括号影响了你。:D

哈！是的，有时我会有点高兴。还是给我点个赞吧。

【参考方案2】：

试试

SELECT
 l.code,
 l.rtl,
 l.name,
 p.title,
 p.description,
 p.keywords
FROM
 language AS l
INNER JOIN product_i18n p ON (p.product_id = :product_id AND p.culture = l.code)
WHERE
 l.status = 1
ORDER BY
 IFNULL(l.sort, l.id)