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前情提要：
公司运营的一个商城系统，忽然发现订单提现功能有问题，有大量的商户体现金额和订单金额不一致。于是产生了需求，需要把提现表和供应商表作为一个结果集，连接上订单表中的订单金额，通过计算订单表的金额和体现表商户提现的金额进行比对，查看商户是多提现了还是少提现了。
下面记录我的查询过程。
查询过程：
刚开始，第一步我以提现表为主表，查询出来相关结果。MySQL 语句如下
SELECT count(ysw.supply_id) AS 提现次数 ,ysw.user_id AS 供应商对应的用户 ID , ysw.supply_id AS 供应商 ID ,SUM(ysw.money) AS 供应商提现总金额 ,
case ysw.pay_type when 10 then 微信 when 20 then 支付宝 else 银行卡 end as 支付方式 ,
ys.supply_name AS 供应商名称 ,ys.money AS 供应商余额 ,ys.freez_money AS 供应商冻结金额（已提现金额）FROM yoshop_supply_withdraw AS ysw LEFT JOIN yoshop_supply AS ys ON ysw.supply_id = ys.supply_id
WHERE ysw.create_time 1647446400 AND ysw.apply_status IN (10,20,40) GROUP BY ysw.supply_id
ORDER BY SUM(ysw.money) DESC ;查询结果如图是正常的：
接下来，我在左链接上订单表的数据，又添加一个了 left join，金额相关数据发生了变化严重不一致, 而且查询时间明显延长，MySQL 语句如下
SELECT count(ysw.supply_id) AS 提现次数 ,ysw.user_id AS 供应商对应的用户 ID , ysw.supply_id AS 供应商 ID ,SUM(ysw.money) AS 供应商提现总金额 ,
case ysw.pay_type when 10 then 微信 when 20 then 支付宝 else 银行卡 end as 支付方式 ,
ys.supply_name AS 供应商名称 ,ys.money AS 供应商余额 ,ys.freez_money AS 供应商冻结金额（已提现金额）,SUM(yo.pay_price)
FROM yoshop_supply_withdraw AS ysw LEFT JOIN yoshop_supply AS ys ON ysw.supply_id = ys.supply_id
LEFT JOIN yoshop_order AS yo ON yo.supply_ids =ysw.supply_id
WHERE ysw.create_time 1647446400 AND ysw.apply_status IN (10,20,40) GROUP BY ysw.supply_id
ORDER BY SUM(ysw.money) DESC ;查询结果对比图如下：
经过实践，我想直接通过左连接查询到提现表金额和订单表金额是行不通的。通过网上查资料，以及在技术群里请教，
优化了思路：把提现的统计好, 把订单的统计好，最后两个结果集再根据供应商 id 做个链接
接下来就是，三步走了，第一步：把提现的统计好，上面第一次尝试的第一步就是了，第二步：把订单表的数据统计好。由于使用系统的原因，我直接使用的订单商品表计算的订单总金额，这一步也是分三步走的，我直接上代码：
1. 查询 yoshop_order 所有进行中，已完成的 订单 id(order_id);
SELECT order_id FROM yoshop_order WHERE order_status IN (10,30);
2. 查询没有退款的订单 ID
SELECT order_id FROM yoshop_order WHERE order_status IN (10,30) AND order_id NOT IN ( SELECT order_id FROM yoshop_order_refund);
3. 查询订单商品表中 所有的订单金额
SELECT supply_id AS 供应商 ID , SUM(total_pay_price) AS 供应商订单总金额 FROM yoshop_order_goods WHERE create_time 1647446400 AND order_pay_status = 0 AND order_id IN(SELECT order_id FROM yoshop_order WHERE order_status IN (10,30) AND order_id NOT IN ( SELECT order_id FROM yoshop_order_refund) ) GROUP BY supply_id
ORDER BY SUM(total_pay_price) DESC ;接下来就是进行把第一步和第二步的查询结果当作派生表，进行左连接查询。我在这一步耗费的时间和精力最多。如果你能认真看完，相信一定会有收货。我在这里把我错误的过程也进行了记录 第一次错误拼接：
SELECT * FROM (SELECT count(ysw.supply_id) AS 提现次数 ,ysw.user_id AS 供应商对应的用户 ID , ysw.supply_id AS supply_id ,SUM(ysw.money) AS 供应商提现总金额 ,
case ysw.pay_type when 10 then 微信 when 20 then 支付宝 else 银行卡 end as 支付方式 ,
ys.supply_name AS 供应商名称 ,ys.money AS 供应商余额 ,ys.freez_money AS 供应商冻结金额（已提现金额）FROM yoshop_supply_withdraw AS ysw LEFT JOIN yoshop_supply AS ys ON ysw.supply_id = ys.supply_id
WHERE ysw.create_time 1647446400 AND ysw.apply_status IN (10,20,40) GROUP BY ysw.supply_id
ORDER BY SUM(ysw.money) DESC ) AS t1
union all // left join , 这里是注释记得删除
SELECT * FROM -- 这里是错误的不应该在查询
(SELECT supply_id AS supply_id , SUM(total_pay_price) AS total_pay_price FROM yoshop_order_goods WHERE create_time 1647446400 AND order_pay_status = 0 AND order_id IN(SELECT order_id FROM yoshop_order WHERE order_status IN (10,30) AND order_id NOT IN (SELECT order_id FROM yoshop_order_refund) ) GROUP BY supply_id
ORDER BY SUM(total_pay_price) DESC ) AS t2
ON t1.suppply_id = t2.suppply_id通过这一次试错，明显看出我把 left join 和 union all 的含义记错了, 并且在拼接的时候重复使用了 select * from。虽然是试错了，但也是有收货的，接下来进行了第二次错误的拼接：
SELECT t1. 提现次数 ,t1. 供应商对应的用户 ID ,t1.supply_id, t1. 支付方式 ,t1. 供应商名称,t1. 供应商余额, t1. 供应商冻结金额（已提现金额）, t2.total_pay_price FROM (SELECT count(ysw.supply_id) AS 提现次数 ,ysw.user_id AS 供应商对应的用户 ID , ysw.supply_id AS supply_id ,SUM(ysw.money) AS 供应商提现总金额 ,
case ysw.pay_type when 10 then 微信 when 20 then 支付宝 else 银行卡 end as 支付方式 ,
ys.supply_name AS 供应商名称 ,ys.money AS 供应商余额 ,ys.freez_money AS 供应商冻结金额（已提现金额）FROM yoshop_supply_withdraw AS ysw LEFT JOIN yoshop_supply AS ys ON ysw.supply_id = ys.supply_id
WHERE ysw.create_time 1647446400 AND ysw.apply_status IN (10,20,40) GROUP BY ysw.supply_id
ORDER BY SUM(ysw.money) DESC ) AS t1
LEFT JOIN
(SELECT supply_id AS supply_id , SUM(total_pay_price) AS total_pay_price FROM
yoshop_order_goods WHERE create_time 1647446400 AND order_pay_status = 0
AND order_id IN(SELECT order_id FROM yoshop_order WHERE order_status IN (10,30)
AND order_id NOT IN (SELECT order_id FROM yoshop_order_refund) )
GROUP BY supply_id
ORDER BY SUM(total_pay_price) DESC ) AS t2
ON t1.suppply_id = t2.suppply_id通过这两次错误的尝试，以及根据尝试过程中 MySQL 给出的错误提示，知道自己是在左连接上使用错误了，应该在开始查询出来所有的字段，left join 后不能在使用 select * 最后，回想了一遍自己所学的 left join 的语法，写出了最后的正确的查询结果
SELECT t1.supply_id 供应商 ID ,t1.supply_name 供应商名称 ,t1.user_id 供应商绑定的用户 ID ,t1.withdrawtime 供应商提现次数 ,t1.supplyallmoney 供应商提现金额 ,t1.payway 供应商提现方式 ,t1.supply_money 供应商账户余额 ,t1.supply_free_money 供应商冻结余额（已提现金额）,
t2.total_pay_price 供应商订单总金额 ,t2.order_id 供应商订单数量
FROM (SELECT count(ysw.supply_id) AS withdrawtime, ysw.user_id AS user_id, ysw.supply_id AS supply_id , SUM(ysw.money) AS supplyallmoney, ysw.alipay_name AS alipay_name ,ysw.alipay_account AS alipay_account, ysw.audit_time as audit_time , ysw.bank_account AS bank_account, ysw.bank_card AS bank_card, ysw.bank_name AS bank_name,
case ysw.pay_type when 10 then 微信 when 20 then 支付宝 else 银行卡 end as payway ,
ys.supply_name AS supply_name, ys.money AS supply_money, ys.freez_money AS supply_free_money
FROM yoshop_supply_withdraw AS ysw LEFT JOIN yoshop_supply AS ys ON ysw.supply_id = ys.supply_id
WHERE ysw.create_time 1647446400 AND ysw.apply_status IN (10,20,40) GROUP BY ysw.supply_id
ORDER BY SUM(ysw.money) DESC ) AS t1
LEFT JOIN
(SELECT supply_id AS supply_id , COUNT(order_id) AS order_id, SUM(total_pay_price) AS total_pay_price
FROM yoshop_order_goods WHERE create_time 1647446400 AND order_pay_status = 0
AND order_id IN( SELECT order_id FROM yoshop_order WHERE order_status IN (10,30)
AND order_id NOT IN ( SELECT order_id FROM yoshop_order_refund) )
GROUP BY supply_id
ORDER BY SUM(total_pay_price) DESC ) AS t2
ON t1.supply_id = t2.supply_id正确的结果截图：
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