1

因此，我遇到了从查询中获取正确数据的问题。

我有下表（人）：

Name  |       xpath        |   value
Derek |  /body/torso/arm   |   left
Derek |  /body/torso/arm   |   right
Derek |  /body/torso/neck  |   Head
Ron   |  /body/torso/neck  |   Head
Ron   |  /body/torso/arm   |   left

所以基本上我试图得到的查询结果是显示差异（两个人之间缺少什么）。

results:
Name1 |       xpath1       |   value1   | Name2  |   xpath2         |   value2
Derek |  /body/torso/arm   |   right    | Ron    |    NULL          |   NULL

我什至可以将以下内容取回

results:
Name1 |       xpath1       |   value1   | Name2  |   xpath2         |   value2
Derek |  /body/torso/arm   |   right    | Ron    |    NULL          |   NULL
Derek |  /body/torso/arm   |   left     | Ron    | /body/torso/arm  |   left  
Derek |  /body/torso/neck  |   Head     | Ron    | /body/torso/neck |   Head

我使用的查询是：

SELECT P.Name , P.xpath, P.value, P1.Name, P2.xpath, P3.value
FROM Person as P
LEFT OUTER JOIN
    Person as P2 ON P.xpath = P2.xpath
WHERE
         P.Name = "Derek"
    AND  P2.Name = "Ron"

无论我尝试什么，我不断得到的结果基本上是重叠的数据，但从来不是我真正想要的，似乎我错过了一些简单的东西或者只是做错了。有什么建议么？最终，我将在 SPROC 中运行它，但能够处理多个名称不仅仅是 2，而且如果我有，Derek、Ron、John、Dawn 等。

4

2 回答 2

2

试一试：

SELECT    a.Name  AS Name1,
          a.xpath AS xpath1,
          a.value AS value1,
          'Ron'   AS Name2,
          b.xpath AS xpath2,
          b.value AS value2
FROM      Person a
LEFT JOIN Person b ON b.Name = 'Ron'
                  AND a.xpath = b.xpath 
                  AND a.value = b.value
WHERE     a.Name = 'Derek' AND
          b.Name IS NULL

SQLFiddle 演示

如果您想将 Derek 与多个名称进行比较，您可以CROSS JOIN对所有名称进行比较（以便名称可以出现在结果集中），以及使用,LEFT JOIN的同一个表，以及在 中指定的名称：xpathvalueCROSS JOIN

SELECT     a.Name  AS Name1,
           a.xpath AS xpath1,
           a.value AS value1,
           b.Name  AS Name2,
           c.xpath AS xpath2,
           c.value AS value2
FROM       Person a
CROSS JOIN (
           SELECT 'Ron' AS Name UNION ALL
           SELECT 'John'        UNION ALL
           SELECT 'Charles'     UNION ALL
           SELECT 'Aaron'
           ) b
LEFT JOIN  Person c ON b.Name  = c.Name 
                   AND a.xpath = c.xpath
                   AND a.value = c.value
WHERE      a.Name = 'Derek' AND
           c.Name IS NULL

SQLFiddle 演示

如果您想在比较的左侧有多个名称（不仅仅是“Derek”），只需更改

a.Name = 'Derek'

到

a.Name <> b.Name

在上面的查询中。

SQLFiddle 演示

编辑：只是为了更进一步：

将所有名称与所有名称进行比较：

SELECT     a.Name  AS Name1,
           a.xpath AS xpath1,
           a.value AS value1,
           b.Name  AS Name2,
           c.xpath AS xpath2,
           c.value AS value2
FROM       Person a
CROSS JOIN (SELECT DISTINCT Name FROM Person) b
LEFT JOIN  Person c ON b.Name  = c.Name 
                   AND a.xpath = c.xpath
                   AND a.value = c.value
WHERE      a.Name <> b.Name AND 
           c.Name IS NULL
于 2012-08-16T17:36:20.370 回答
0

尝试使用 EXCEPT 联合：

WITH tbl (name, xpath, value) as
    (values
        ('Derek','/body/torso/arm','left'),
        ('Derek','/body/torso/arm','right'),
        ('Derek','/body/torso/neck','Head'),
        ('Ron','/body/torso/neck','Head'),
        ('Ron','/body/torso/arm','left')
    )
SELECT xpath, value 
FROM tbl 
WHERE name = 'Derek'
    EXCEPT
        SELECT xpath, value 
        FROM tbl 
        WHERE name = 'Ron'
于 2012-08-16T18:15:28.267 回答