使用SUM（）的慢速MySQL查询

我必须在我的代码中运行两个查询来获得租户余额。但是，这些查询太慢

第一个查询，我得到所有租户及其单位名称：

SELECT t.TenantID 
  FROM Tenants t
  JOIN Units u
    ON t.UnitID = u.UnitID
 Where t.Prospect = 2 
   AND t.PropertyID = 8
 ORDER 
    BY CONCAT(Left(Replace(UnitName,'-',''),2),
              REPEAT('0', (10-CHAR_LENGTH(UnitName))),
              Right(Replace(UnitName,'-',''),
                    CHAR_LENGTH(Replace(UnitName,'-',''))-2
             )     )

它返回500行

然后我得到了4种条件下的余额。此查询将位于第一个查询循环内：

Select
        SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) AS TotalDebit,
        SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) AS HousingDebit,
        SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) AS TotalCredit,
        SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) AS HousingCredit
    From TenantTransactions
    Where TenantID= FirstQuery.TenantID

---

我是不是做错了？运行大约需要1分钟。

使用

分组方式在单个查询中执行此操作

试着这样做：

SELECT t.TenantID, TotalDebit, HousingDebit, TotalCredit, HousingCredit
  FROM Tenants t
  JOIN Units u ON t.UnitID = u.UnitID
  LEFT JOIN (
        Select
          TenantID,
          SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) AS TotalDebit,
          SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) AS HousingDebit,
          SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) AS TotalCredit,
          SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) AS HousingCredit
        From TenantTransactions
       Group By TenantID
       ) sums ON sums.TenantID = t.TenantID
 Where t.Prospect = 2 
   AND t.PropertyID = 8
 ORDER 
    BY CONCAT(Left(Replace(UnitName,'-',''),2),REPEAT('0', (10-CHAR_LENGTH(UnitName))),Right(Replace(UnitName,'-',''),CHAR_LENGTH(Replace(UnitName,'-',''))-2))

内部查询可能仍会运行一段时间，但只运行一次

在
租户交易
上尝试包含以下列的复合覆盖索引：
（租户ID、TransactionTypeID、ChargeTypeID、TransactionMount）
，以优化查询中的金额

在
租户
上尝试一个包含
（PropertyID，Prospect）
列的复合索引。
下面是另一种使用子查询的方法。您知道，性能问题可能不是数据库性能，而是数据库和应用程序服务器之间的来回。因此，这是一个单一的查询将有所帮助

SELECT t.TenantID,
  (SELECT SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) From TenantTransactions TT WHERE TT.TenantID=t.TenantID) AS TotalDebit,
  (SELECT SUM(CASE WHEN TransactionTypeID = 1 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) From TenantTransactions TT WHERE TT.TenantID=t.TenantID) AS HousingDebit,
  (SELECT SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID != 6 THEN TransactionAmount ELSE 0 END) From TenantTransactions TT WHERE TT.TenantID=t.TenantID) AS TotalCredit,
  (SELECT SUM(CASE WHEN TransactionTypeID = 2 AND ChargeTypeID = 6 THEN TransactionAmount ELSE 0 END) From TenantTransactions TT WHERE TT.TenantID=t.TenantID) AS HousingCredit  
  FROM Tenants t
  JOIN Units u
    ON t.UnitID = u.UnitID
 Where t.Prospect = 2 
   AND t.PropertyID = 8
 ORDER 
    BY CONCAT(Left(Replace(UnitName,'-',''),2),REPEAT('0', (10-CHAR_LENGTH(UnitName))),Right(Replace(UnitName,'-',''),CHAR_LENGTH(Replace(UnitName,'-',''))-2))

你给你的表编索引了吗？查询中的函数调用太多。这绝对是反应迟钝的原因。但是，要有一个更好的。在解决方案中，您需要指定表结构、索引和键是的，租户和租户事务表由租户TID链接。TenantID是租户PK，租户交易FK请阅读此内容。请特别注意有关查询性能的部分。请您的问题提供我们需要的基本信息。谢谢您。。。它跑得很快。由于某些原因，某些余额返回的值与我的慢速查询不同。您是否找到导致数据差异的原因？是的，抱歉。你的问题很完美。我改变了一个条件。谢谢，里面有多余的逗号。现在已经修复了。谢谢，但是它仍然返回语法错误，因为结尾在案例中。我正在使用MySQL