需要帮助组合两个 MySQL 查询答案

【问题标题】：Need Help Combining Two MySQL Queries需要帮助组合两个 MySQL 查询
【发布时间】：2014-01-06 08:00:20
【问题描述】：

我在 SQL 方面并不出色，也不知道如何做到这一点。这是我目前遇到的两个问题。

SELECT TicketID_PK, SubProjectID_FK, ProjectID_FK, CustomerID_FK, TicketDate, TicketNumber, 
SignOff, WorkOrder, ClientPO, TicketType, Description, Processed 
FROM Tickets 
INNER JOIN CustomersSubProjects ON Tickets.SubProjectID_FK = CustomersSubProjects.SubProjectID_PK 
INNER JOIN CustomersProjects ON CustomersSubProjects.ProjectID_FK = CustomersProjects.ProjectID_PK 
WHERE TicketID_PK = 1

SELECT ROUND(WCB+Vacation+Stat+UIC+CPP+Overhead,2) AS Total 
FROM EmployeeFormula 
WHERE EffectiveDate <= $TicketDate
ORDER BY EffectiveDate DESC LIMIT 1

我将 TicketDate 保存为 $TicketDate 并在第二个查询中使用它，但我确信有一种方法可以结合这两个查询来避免这种情况。任何帮助将不胜感激。

编辑：我需要通过将 TicketDate 列（在门票表中）与 EffectiveDate 列进行比较来选择 EmployeeFormula Total（如第二个查询中所示）。所以结果应该是这样的：

TicketID_PK     SubProjectID_FK     ProjectID_FK    CustomerID_FK   TicketDate  TicketNumber    Total
1   1   1   1   2014-01-05  1-0501-00   30.78

【问题讨论】：

嗯加入员工公式？
不清楚您所说的“组合”是什么意思。您需要向我们展示表 Tickets、CustomerProjects、CustomerSubProjects 和 EmployeeFormula 的定义，这是您想要的输出示例，并在这些表中采样输入数据以生成输出。

标签： mysql sql

【解决方案1】：

像子查询一样使用。

SELECT TicketID_PK, SubProjectID_FK, ProjectID_FK, CustomerID_FK, TicketDate, TicketNumber, 
SignOff, WorkOrder, ClientPO, TicketType, Description, Processed, (SELECT ROUND(WCB+Vacation+Stat+UIC+CPP+Overhead,2) FROM EmployeeFormula WHERE EffectiveDate <= TicketDate ORDER BY EffectiveDate DESC LIMIT 1) AS Total
FROM Tickets 
INNER JOIN CustomersSubProjects ON Tickets.SubProjectID_FK = CustomersSubProjects.SubProjectID_PK 
INNER JOIN CustomersProjects ON CustomersSubProjects.ProjectID_FK = CustomersProjects.ProjectID_PK 
WHERE TicketID_PK = 1

【讨论】：

这很简单，谢谢。我以前没有真正使用过子查询，并认为我必须加入。