优化这段sql SELECT seller_username, trim( substring_index( platform_order_code, '_CP', 1 )) AS platform_order_code, SUM( success_fee ) AS success_fee_sum, SUM( success_fee_convert ) AS success_fee_rmb_sum, SUM( daily_sell_price / rmb_exchange ) AS daily_sell_price_sum, SUM( daily_sell_price ) AS daily_sell_price_rmb_sum, MIN( shipments_time ) AS shipments_time_min, MIN( rmb_exchange ) AS rmb_exchange_min FROM t_order_mounth202305 WHERE 1 = 1 AND platform = "Walmart" GROUP BY seller_username, platform_order_code
时间: 2023-08-05 22:04:29 浏览: 96
这段 SQL 语句看起来已经相当优化了。但是,我还是能给你一些建议来进一步优化它:
1. 索引:确保 `t_order_mounth202305` 表中的 `platform` 列上有索引,这将提高查询性能。
2. 选择性:确认 `platform` 列的值 "Walmart" 在表中具有足够的选择性。如果大部分行都是 "Walmart",那么索引可能不会被使用。在这种情况下,你可以考虑删除 `AND platform = "Walmart"` 条件。
3. 聚合函数:聚合函数在查询中使用了多次,这可能会导致性能下降。你可以尝试将这些聚合函数移到子查询中,在子查询中进行计算,并将结果与主查询关联。
具体来说,以下是对 SQL 查询的优化建议:
```sql
SELECT
t.seller_username,
t.platform_order_code,
t.success_fee_sum,
t.success_fee_rmb_sum,
t.daily_sell_price_sum,
t.daily_sell_price_rmb_sum,
t.shipments_time_min,
t.rmb_exchange_min
FROM (
SELECT
seller_username,
TRIM(SUBSTRING_INDEX(platform_order_code, '_CP', 1)) AS platform_order_code,
SUM(success_fee) AS success_fee_sum,
SUM(success_fee_convert) AS success_fee_rmb_sum,
SUM(daily_sell_price / rmb_exchange) AS daily_sell_price_sum,
SUM(daily_sell_price) AS daily_sell_price_rmb_sum,
MIN(shipments_time) AS shipments_time_min,
MIN(rmb_exchange) AS rmb_exchange_min
FROM t_order_mounth202305
WHERE platform = "Walmart"
GROUP BY seller_username, platform_order_code
) AS t;
```
这样做的目的是将聚合函数移动到子查询中,然后将子查询的结果与外部查询关联。这可能会提高查询性能。
请注意,优化 SQL 查询是一项复杂的任务,具体的优化策略可能因数据库架构、数据量和查询需求而异。因此,建议在进行任何更改之前先在测试环境中进行验证。
阅读全文