Question

我无法在SQL Server中使用JOIN从两个表中获取完整记录。

我需要ID=1

这两个表的完整详细信息

我有表格Blog＆amp; Category。

Blog表：

ID  BlogTitle       CatID       Public
--------------------------------------
1   Title One       10          1
2   Title Two       0           1
3   Title Three     NULL        1

Category表：

CatID   CatName
--------------------
10      Category One
20      Category Two

查询

SELECT 
    ID, BlogTitle, c.CatID, CatName
FROM 
    Blog b 
FULL OUTER JOIN 
    Category C ON b.CatID = c.CatID
WHERE 
    Public = 1 AND ID = 1

从这个查询中，我得到以下结果：

ID  BlogTitle       CatID       CatName 
----------------------------------------
1   Title One       NULL        NULL

虽然我期待以下结果

ID  BlogTitle       CatID       CatName 
----------------------------------------------
1   Title One       10          Category One

我做了一些尝试，但我不确定我做错了什么。

Answer 1

尝试：

SELECT Blog.ID, Blog.BlogTitle, Blog.CatID, Category.CatName
FROM Blog
INNER JOIN Category
ON Blog.CatID = Category.CatID
WHERE
Blog.ID = 1
AND
Blog.Public = 1

Answer 2

将条件从WHERE移至ON以获得外部联接结果：

SELECT ID, BlogTitle, c.CatID, CatName
FROM Blog b
FULL OUTER JOIN Category C
    ON  b.CatID = c.CatID
    AND Public = 1 AND ID = 1

Answer 3

您的ID = 1语句中有where，并且只有一条记录符合此条件。这就是你没有获得所有记录的原因。

尝试此操作，而不是将条件放在where中，将其放入ON子句中。像

SELECT ID, BlogTitle, c.CatID, CatName FROM Blog b FULL OUTER JOIN Category C ON (b.CatID = c.CatID and Public = 1 AND ID = 1)

Answer 4

Use JOIN to get your result :

  CREATE TABLE #table ( ID INT ,   BlogTitle VARCHAR(100) , CatID INT ,   
   _Public  INT)
  CREATE TABLE #table1 ( CatID INT ,   CatName VARCHAR(100) )

   INSERT INTO #table1 ( CatID  ,   CatName )
   SELECT 10,'Category One' UNION ALL
   SELECT 20,'Category Two'

   INSERT INTO #table ( ID ,   BlogTitle  , CatID , _Public  )
   SELECT 1,'Title One',10,1 UNION ALL
   SELECT 2,'Title Two',0,1 UNION ALL
   SELECT 3,'Title Three',NULL,1

   SELECT ID,  BlogTitle ,  #table.CatID ,      CatName 
   FROM #table
   JOIN #table1 ON #table.CatID = #table1.CatID
   WHERE Id = 1

Answer 5

SELECT B.ID,B.BlogTitle,C.CatID, C.CatName FROM
(SELECT ID, BlogTitle,CatID FROM Blog  WHERE Public = 1 AND ID = 1) B
 FULL OUTER JOIN Category C
  ON b.CatID = c.CatID

如何从SQL Server 2008 R2中的两个表中获取完整记录

5 个答案: