MySQL语句的不同格式/效率

这是一个运行此语句的不同方式的问题，或者是一种使其更有效的方式

本声明旨在列出最快离开现场的所有员工，但他们也必须在今天到达现场

SELECT 
    e.EmpName,
    cs.SiteName
FROM
    Employee e
INNER JOIN
    EmployeeAssignment ea
ON
    e.EmpId = ea.EmpId
INNER JOIN
    CustomerSite cs
ON
    ea.CustId = cs.CustId
WHERE 
    e.EmpId IN
    (
    SELECT
        ea.EmpId
    FROM
        EmployeeAssignment ea
    WHERE
         ea.EndDate IN
            (
            SELECT 
                MIN(ea.EndDate)
            FROM 
                 EmployeeAssignment ea
             WHERE
                GETDATE() BETWEEN ea.StartDate AND ea.EndDate
             GROUP BY 
                CustId
             ));

如果有人想用更好的方式写这封信，请回复谢谢：）

试试这个

SELECT  
    e.EmpName, 
    cs.SiteName 
FROM 
    Employee e 
INNER JOIN 

(
 SELECT  custid,empid from EmployeeAssignment ea1 where Enddate=( 
             select MIN(ea.EndDate) 
            FROM  
                 EmployeeAssignment ea 
             WHERE 
                GETDATE() BETWEEN ea.StartDate AND ea.EndDate 
                and ea.custid=ea1.custid
             )
) as ea
ON 
    e.EmpId = ea.EmpId 
INNER JOIN 
    CustomerSite cs 
ON 
    ea.CustId = cs.CustId 

---

这可能有效，也可能无效：

SELECT 
    e.EmpName,
    cs.SiteName
FROM
    Employee e
INNER JOIN
    EmployeeAssignment ea
ON
    e.EmpId = ea.EmpId
INNER JOIN
    CustomerSite cs
ON
    ea.CustId = cs.CustId
GROUP BY   
e.EmpName,
cs.SiteName
HAVING ea.EndDate = 
        (
        SELECT 
            MIN(ea.EndDate)
        FROM 
             EmployeeAssignment ea
         WHERE
            GETDATE() BETWEEN ea.StartDate AND ea.EndDate);

---

这不起作用，因为如果ea.EndDate不在聚合或order by子句中，则不能在having子句中包含它，但在ordeby子句中，它不会显示所有结果。感谢您的尝试，您可以将ea.EndDate放在MIN aggregate之后，因为我们正在寻找最小日期，因为最后一个ea.CustId是无效的列名？？