Question

我尝试了UNION，但它没有工作，它说＃1221 - UNION和ORDER BY的使用不正确。

SELECT members.Name, friends.MemberNumber1
FROM friends
INNER JOIN members ON friends.MemberNumber1= members.MemNo
WHERE friends.MemberNumber2 LIKE 1
ORDER BY members.Name

UNION

SELECT members.Name, friends.MemberNumber2
FROM friends
INNER JOIN members ON friends.MemberNumber2= members.MemNo
WHERE friends.MemberNumber1 LIKE 1
ORDER BY members.Name

这两个查询都可以自行运行，但我试图将它们放在一个查询中，因为我想对每个查询进行查询。之后在JSTL中的结果集。我也尝试为friends.MemberNumber1和friends.MemberNumber2创建一个别名，但它没有改变任何东西。也许还有一个更简单的查询，我只是没有看到。或者我绝对需要进行两次查询？

由于

Answer 1

您需要将UNION放入子查询中，然后对整个事物进行排序。

SELECT *
FROM (
    SELECT members.Name, friends.MemberNumber1
    FROM friends
    INNER JOIN members ON friends.MemberNumber1= members.MemNo
    WHERE friends.MemberNumber2 LIKE 1

    UNION

    SELECT members.Name, friends.MemberNumber2
    FROM friends
    INNER JOIN members ON friends.MemberNumber2= members.MemNo
    WHERE friends.MemberNumber1 LIKE 1) AS u
ORDER BY u.Name

Answer 2

(SELECT members.Name,     friends.MemberNumber1
FROM friends
INNER JOIN members ON         friends.MemberNumber1= members.MemNo
WHERE friends.MemberNumber2 LIKE 1)

UNION

(SELECT members.Name,     friends.MemberNumber2
FROM friends
INNER JOIN members ON friends.MemberNumber2= members.MemNo
WHERE friends.MemberNumber1 LIKE 1)
ORDER BY members.Name

Answer 3

您可以执行派生表，然后按顺序排序。列名必须匹配。我知道这个答案很接近Barmar，但第二列的aliasName很重要。你也可以查看UNION和UNION ALL之间的区别，我通常使用后者。

SELECT Name , MemberNumber
FROM (
    SELECT members.Name, friends.MemberNumber1 as MemberNumber
    FROM friends
    INNER JOIN members ON friends.MemberNumber1= members.MemNo
    WHERE friends.MemberNumber2 LIKE 1

    UNION ALL

    SELECT members.Name, friends.MemberNumber2 as MemberNumber
    FROM friends
    INNER JOIN members ON friends.MemberNumber2= members.MemNo
    WHERE friends.MemberNumber1 LIKE 1) AS derived1
ORDER BY derived1.Name

Answer 4

它还满足您的查询逻辑？

SELECT members.Name, friends.MemberNumber1
FROM friends
INNER JOIN members ON friends.MemberNumber1= members.MemNo 
WHERE friends.MemberNumber2 LIKE 1 OR friends.[primarykey] IN (

SELECT friend.[primarykey]
FROM friends
INNER JOIN members ON friends.MemberNumber2= members.MemNo
WHERE friends.MemberNumber1 LIKE 1

)

Answer 5

试试这个：

SELECT 
            *
FROM
(
    SELECT 
            Name = members.Name,
            MemberNumber = friends.MemberNumber1
    FROM    
            friends
    INNER JOIN 
            members 
            ON friends.MemberNumber1= members.MemNo
    WHERE 
            friends.MemberNumber2 LIKE 1
    UNION ALL
    SELECT 
            Name = members.Name, 
            MemberNumber = friends.MemberNumber2
    FROM 
            friends
    INNER JOIN 
            members ON friends.MemberNumber2= members.MemNo
    WHERE 
            friends.MemberNumber1 LIKE 1

) Unioned
ORDER BY 
            Unioned.Name

如果UNION ALL出现问题，请尝试UNION

将两个SELECT合并为同一个表中的一个？

5 个答案: