Mysql基于多种情况获取记录答案

【问题标题】：Mysql Fetch Records Based on Multiple CasesMysql基于多种情况获取记录
【发布时间】：2016-10-01 12:06:18
【问题描述】：

我确实有 Mercer_credit_history 表，我在其中存储商家信用、借记和交易类型。

我想根据交易类型对 CREDIT 或 DEBIT 求和。

记录

我试过这个：

选择 SUM(ABS(debit)) 作为 dealer_credit FROM Mercer_credits_history WHERE transaction_type='premium_debit'和merchant_id='x'

联合

SELECT SUM(ABS(credit)) as dealer_margin_earned FROM Mercer_credits_history WHERE transaction_type='margin_credit'和merchant_id='x'

并得到输出

如果我能有更好的查询以及单独的键值对中的值，我将不胜感激

【问题讨论】：

标签： mysql database

【解决方案1】：

SELECT 
    SUM(CASE(WHEN transaction_type='premium_debit') THEN debit ELSE 0)) as dealer_credit, 
    SUM(CASE(WHEN transaction_type='margin_credit') THEN credit ELSE 0)) as dealer_margin_earned 
    FROM merchant_credits_history 
    WHERE merchant_id='x';

因此，您会为每个商家 ID 获得一对贷记、借记值。

【讨论】：

【解决方案2】：

SELECT SUM(Debit), SUM(CREDIT) FROM 
   (SELECT 
      CASE WHEN transaction_type='premium_debit' THEN debit ELSE 0 END as Debit, 
      CASE WHEN transaction_type='margin_credit' THEN credit ELSE 0 END as Credit
   FROM Customers WHERE merchant_id='x')

【讨论】：

【解决方案3】：

试试这个：

SELECT SUM(ABS(credit)) as Credit, SUM(ABS(debit)) AS Debit, 
transaction_type FROM merchant_credits_history merchant_id='x'
GROUP BY (transaction_type);

【讨论】：