Question

我正在修改我的考试，我对SQL查询有点挣扎..

我的任务是：

编写SQL查询以列出所有客户端的全名参加艾伦摩尔的课程，按姓氏的字母顺序排列（即 Lname列）

客户端

Cid Fname Lname Fitness
C129 Julie Summer 1
C525 Max Hedrum 3
C628 John Long 3
C772 Warren Peace 2
C829 Anna Heart 2

程序

Code Title Fitness
AR02 Aerobics 2
EN99 Endurance 3
TU10 Tune-Up 1
UB01 Upper-Body 2
YG02 Yoga 1

员工

Sid Fname Lname Position Salary
S09 Jenny Sayer Psychologist 23500
S22 Allen Moore Instructor 21500
S28 Polly Purves Instructor 19000
S35 Jim Shoe Instructor 18000
S55 Mark Spencer Manager 25500

类

Code Sid Cid
AR02 S35 C772
EN99 S22 C525
TU10 S35 C129
UB01 S28 C628
YG02 S22 C829
YG02 S22 C12

是这样的：

SELECT Cliente.Fname, Cliente.Lname
FROM Staff, Class, Cliente
WHERE  Staff.Sid = Class.Sid AND Staff.Fname = "Allen" AND Staff.Lname = "Moore 
AND Class.Cid = Cliente.Cid
GROUP BY Cliente.lName ASC;

谢谢！

Answer 1

select c.fname + ' ' + c.lname
from Client c
inner join Class cl
on c.cid = cl.cid
inner join Staff s
on s.sid = cl.sid
where s.fname = 'allen'
and s.lname = 'moore'
order by c.lname

Answer 2

为JOIN使用不同的别名和更流行的约定，但您的查询也应该有效。此外，ORDER BY升序是默认值，因此ASC是可选的......

SELECT CLNT.Fname, CLNT.Lname
FROM Class AS CLS
     INNER JOIN Client AS CLNT ON CLS.Cid = CLNT.Cid
     INNER JOIN Staff AS S ON CLS.Sid = S.Sid
WHERE S.Fname = 'Allen'
      AND S.Lname = 'Moore'
ORDER BY CLNT.Lname;

Answer 3

尝试使用JOIN ... ON子句。

http://www.w3schools.com/sql/sql_join_inner.asp

Answer 4

您的查询中的GROUP BY必须去，您不必聚合任何东西。我更喜欢连接的SQL92语法：

SELECT 
    Client.Fname, Client.Lname
FROM 
   Staff
INNER JOIN
Class ON Staff.Sid = Class.Sid AND Staff.Fname = "Allen" AND Staff.Lname = "Moore"
INNER JOIN 
Client ON Class.Cid = Cliente.Cid
ORDER BY Cliente.lName ASC;

Answer 5

由于实际上没有使用其他表中的信息，为什么要加入？

 SELECT FName, LName
 FROM Client
 WHERE
    Cid IN (
        SELECT Cid
        FROM Class
        WHERE Sid = (
            SELECT Sid FROM Staff WHERE FName = 'Allen' AND LName = 'Moore'
        )
    )
 ORDER BY LName ASC;

进行SQL查询（交叉表）

5 个答案: