Question

任何人都可以帮我优化此查询。我无法执行它，因为phpMyAdmin连接超时，我无权更改超时参数。

这是一个查询：

INSERT INTO `goods` (`goods_id`, `price`, `name`)
SELECT `sales_goods`.`goods_id`, `sales_goods`.`price`, `sales_goods`.`goods_id`
FROM `sales_goods`
WHERE `sales_goods`.`sales_goods_id`
IN (
    SELECT MAX(`sales_goods`.`sales_goods_id`)
    FROM `sales_goods`
    WHERE `sales_goods`.`sales_goods_id`
    IN (
        SELECT `sales_goods`.`sales_goods_id` FROM `sales_goods` 
        WHERE `sales_goods`.`goods_id` NOT IN (SELECT `goods`.`goods_id` FROM `goods`)
    )
    GROUP BY `sales_goods`.`goods_id`
)

Answer 1

除了确保您的表格属性已编入索引外，您可以将IN子查询替换为INNER JOIN，将NOT IN子查询替换为LEFT JOIN/IS NULL，这样可以提高性能：< / p>

INSERT INTO `goods` (`goods_id`, `price`, `name`)
SELECT  `sales_goods`.`goods_id`, 
        `sales_goods`.`price`, 
        `sales_goods`.`goods_id`
FROM    `sales_goods`
        INNER JOIN
        (   SELECT  MAX(`sales_goods`.`sales_goods_id`)
            FROM    `sales_goods`
                    LEFT JOIN `goods`
                        ON `goods`.`goods_id` = `sales_goods`.`goods_id`
            WHERE   `goods`.`goods_id` IS NULL
            GROUP BY `sales_goods`.`goods_id`
        ) MaxSalesGoods
            ON MaxSalesGoods.sales_goods_id = `sales_goods`.`sales_goods_id`

优化MySQL查询，因为它有时间

1 个答案: