Question

REntal表：

CREATE TABLE RENTAL
(
TransactionNo int NOT NULL AUTO_INCREMENT,
MemberID int NOT NULL, 
ItemNo char(3) NOT NULL,
RentalEmployeeID varchar(30),
ReturnEmployeeID varchar(30), 
Checkout_date DATE, 
Checkin_date DATE,
Return_date DATE,
ItemQuantity int(11) NOT NULL,
TotalPrice DOUBLE(10,2) NOT NULL,
ItemFee DOUBLE(10,2),
PRIMARY KEY(TransactionNo),
FOREIGN KEY(MemberID) REFERENCES Member(MemberID),
FOREIGN KEY(ItemNo) REFERENCES Item(Itemno),
FOREIGN KEY(RENTALEMPLOYEEID) REFERENCES Employee(EmployeeID),
FOREIGN KEY(RETURNEMPLOYEEID) REFERENCES Employee(EmployeeID)
)

我正在尝试检索所有为Joe Smith办理入住或退房的人，但我不仅可以办理入住手续或办理入住手续，而且不能同时办理入住手续。我需要一个嵌套子句吗？

SELECT  r.ItemNo, 
        i.Category, 
        i.Style, 
        i.Description, 
        r.`CheckIn_date`, 
        r.`Checkout_date`, 
        e.Fname, 
        e.Lname   
FROM    MEMBER AS m, 
        ITEM AS i, 
        RENTAL AS r, 
        Employee e 
WHERE   m.MemberID = r.MemberID 
AND     m.Fname = 'Joe’ 
AND     m.Lname=’Smith’ 
AND     r.ItemNo = i.ItemNo 
AND     r.RentalEmployeeID = e.EmployeeID

Answer 1

我想你是说没有选择包含签到和结帐的记录。查询阻止了这一点。必须是数据缺少这种情况。

Answer 2

你可以用两个连接替换它，我认为......

SELECT  r.ItemNo, 
        i.Category, 
        i.Style, 
        i.Description, 
        r.`CheckIn_date`, 
        r.`Checkout_date`, 
        e_rent.Fname, 
        e_rent.Lname,
        e_rtn.Fname,
        e_rtn.Lname  
FROM    ITEM AS i, 
        RENTAL AS r, 
        Member m
LEFT JOIN Employee e_rent ON (r.RentalEmployeeID = e_rent.ID)
LEFT JOIN Employee e_rtn ON (r.RentalEmployeeID = e_rtn.ID)
WHERE   m.MemberID = r.MemberID 
AND     m.Fname = 'Joe’ 
AND     m.Lname=’Smith’ 
AND     r.ItemNo = i.ItemNo

mySQL查询检索问题

2 个答案: