查询是否在数据库的其他地方引用了外键 [英] Query to find out if foreign key is referenced anywhere else in the database

问题描述

我想从这个表中返回所有的内容+表示记录是否被其他地方引用为外键的一列。

>

IE：

  Animal_Id名称
 1 Cat 
 2狗
 3 Parrot 
  

我想返回这个：

  AnimalId名称引用
 1猫真
 2狗假
 3 Parrot真
  
  select count（*）from eachTable其中AnimalID = 1  
 
 
 
有没有人有关于如何做这件事的片段？ 
 
解决方案
  
 
 
  SELECT OO.Animal_ID，OO.Name，CASE WHEN XX.REFERENCED IS NULL THEN'false'ELSE'true'END引用
从动物OO 
 OUTER APPLY（SELECT SUM（1）REFERENCED 
 FROM（SELECT FkAnimal_ID FROM AnimalRef1 RR WHERE RR.FkAnimal_ID = OO。 Animal_ID UNION ALL 
 SELECT FkAnimal_ID FROM AnimalRef2 RR WHERE RR.FkAnimal_ID = OO.Animal_ID UNION ALL 
 SELECT FkAnimal_ID FROM AnimalRef3 RR WHERE RR.FkAnimal_ID = OO.Animal_ID）II）XX 
  
如果你不知道所有的FK表，你可以使用system met一个数据表来生成一个UNION ALL查询集合到一个表中，然后你可以复制&粘贴到您的查询中：
 
 pre $  WITH AKT AS（SELECT f.name AS ForeignKey 
，OBJECT_NAME（f.parent_object_id） AS TableName 
，COL_NAME（fc.parent_object_id，fc.parent_column_id）AS ColumnName 
，OBJECT_NAME（f.referenced_object_id）AS ReferenceTableName 
，COL_NAME（fc.referenced_object_id，fc.referenced_column_id）AS ReferenceColumnName 
 FROM sys.foreign_keys AS f 
 INNER JOIN sys.foreign_key_columns AS fc ON f.OBJECT_ID = fc.constraint_object_id 
 WHERE f.referenced_object_id = object_id（'Animal'））
 SELECT' SELECT'+ ColumnName +'FROM'+ TableName +'WHERE RR。'+ ColumnName +'= OO。'+ ReferenceColumnName +'UNION ALL'
 FROM AKT 
  pre> 
 
 
对于使用递归CTE的单个查询来说，整个事情是这样的： 
 
 
  DECLARE @QUERY NVARCHAR（ MAX）
 
加上AKT AS（SELECT ROW_NUMBER（）OVER（ORDER BY f.name）RN，f.name AS ForeignKey 
，OBJECT_NAME（f.parent_object_id）AS TableName 
 ，COL_NAME（fc.parent_object_id，fc.parent_column_id）AS ColumnName 
，SCHEMA_NAME（oo.schema_id）SchemaName 
，OBJECT_NAME（f.referenced_object_id）AS ReferenceTableName 
，COL_NAME（fc.referenced_object_id，fc .referenced_column_id）AS ReferenceColumnName 
 FROM sys.foreign_keys AS f 
 INNER JOIN sys.foreign_key_columns AS fc ON f.OBJECT_ID = fc.constraint_object_id 
 INNER JOIN sys.objects oo ON oo.object_id = fc .referenced_object_id 
 WHERE f.referenced_object_id = object_id（'Animal'））
 
，bs AS（SELECT AKT.RN 
，'SELECT'+ ColumnName +'FROM'+ SchemaName +'。'+ TableName +'WHERE'+ Co （bs.SubQuery）AS VARCHAR（MAX））加入
 FROM（a）（bs.RN，CAST（RTRIM（bs.SubQuery）AS VARCHAR（MAX））lumnName +'= OO。'+ ReferenceColumnName SubQuery 
 FROM AKT） bs 
 WHERE bs.RN = 1 
 UNION ALL 
 SELECT bs2.RN，CAST（re.Joined +'UNION ALL'+ ISNULL（RTRIM（bs2.SubQuery），''）AS VARCHAR（MAX））加入
 FROM re，bs bs2 
 WHERE re.RN = bs2.RN  -  1）
，fi AS（SELECT ROW_NUMBER（）OVER（ORDER BY RN DESC）RNK ，加入
 FROM re）
 SELECT @QUERY ='SELECT OO.Animal_ID，OO.Name，CASE WHEN XX.REFERENCED IS NULL THEN'NO''ELSE''是''END引用
从动物OO 
 OUTER APPLY（SELECT SUM（1）REFERENCED 
 FROM（'+ Joined +'）II）XX'
 FROM fi 
 RNK = 1 
 
 EXEC（@QUERY）
  
 
I have table Animal.


I want to return everything from this table + one column which denotes if record is referenced anywhere else as a foreign key.

I.E.:  
Animal_Id    Name  
    1        Cat
    2        Dog
    3        Parrot
I want to return this:
AnimalId    Name     Referenced 
    1        Cat         true
    2        Dog         false
    3        Parrot      true
by 'referenced' I mean if a specific Animal_Id was referenced in any other table in the database as a foreign key. I think I first can query information_schema and find out what tables contain this foreign key and then use loop and dynamic sql to execute

select count(*) from eachTable where AnimalID = 1

Does anyone have a snippet on how to do that?
解决方案
This should do it:
SELECT OO.Animal_ID, OO.Name, CASE WHEN XX.REFERENCED IS NULL THEN 'false' ELSE 'true' END Referenced
FROM   Animal OO
       OUTER APPLY (SELECT SUM(1) REFERENCED
                    FROM   (SELECT FkAnimal_ID FROM AnimalRef1 RR WHERE RR.FkAnimal_ID = OO.Animal_ID UNION ALL
                            SELECT FkAnimal_ID FROM AnimalRef2 RR WHERE RR.FkAnimal_ID = OO.Animal_ID UNION ALL
                            SELECT FkAnimal_ID FROM AnimalRef3 RR WHERE RR.FkAnimal_ID = OO.Animal_ID) II) XX
If you don't know all the FK tables, you can use system meta-data tables to generate that collection of UNION ALL queries into a table, which you could then copy & paste into your query:
WITH AKT AS ( SELECT f.name AS ForeignKey
                    ,OBJECT_NAME(f.parent_object_id) AS TableName
                    ,COL_NAME(fc.parent_object_id, fc.parent_column_id) AS ColumnName
                    ,OBJECT_NAME (f.referenced_object_id) AS ReferenceTableName
                    ,COL_NAME(fc.referenced_object_id, fc.referenced_column_id) AS ReferenceColumnName
              FROM   sys.foreign_keys AS f
                     INNER JOIN sys.foreign_key_columns AS fc ON f.OBJECT_ID = fc.constraint_object_id
              WHERE  f.referenced_object_id = object_id('Animal'))
SELECT 'SELECT ' + ColumnName + ' FROM ' + TableName + ' WHERE  RR.' + ColumnName + ' = OO.' + ReferenceColumnName + ' UNION ALL'
FROM   AKT
And for the whole thing in a single query using a recursive CTE:
DECLARE @QUERY NVARCHAR(MAX)

WITH AKT AS ( SELECT ROW_NUMBER() OVER (ORDER BY f.name) RN, f.name AS ForeignKey
                    ,OBJECT_NAME(f.parent_object_id) AS TableName
                    ,COL_NAME(fc.parent_object_id, fc.parent_column_id) AS ColumnName
                    ,SCHEMA_NAME(oo.schema_id) SchemaName
                    ,OBJECT_NAME (f.referenced_object_id) AS ReferenceTableName
                    ,COL_NAME(fc.referenced_object_id, fc.referenced_column_id) AS ReferenceColumnName
              FROM   sys.foreign_keys AS f
                     INNER JOIN sys.foreign_key_columns AS fc ON f.OBJECT_ID = fc.constraint_object_id
                     INNER JOIN sys.objects oo ON oo.object_id = fc.referenced_object_id
              WHERE  f.referenced_object_id = object_id('Animal'))

    ,bs AS (SELECT AKT.RN
                  ,'SELECT ' + ColumnName + ' FROM ' + SchemaName + '.' + TableName + ' WHERE ' + ColumnName + ' = OO.' + ReferenceColumnName  SubQuery
            FROM   AKT)
    ,re AS (SELECT bs.RN, CAST(RTRIM(bs.SubQuery) AS VARCHAR(MAX)) Joined
            FROM   bs
            WHERE  bs.RN = 1
            UNION  ALL
            SELECT bs2.RN, CAST(re.Joined + ' UNION ALL ' + ISNULL(RTRIM(bs2.SubQuery), '') AS VARCHAR(MAX)) Joined
            FROM   re, bs bs2 
            WHERE  re.RN = bs2.RN - 1 )
    ,fi AS (SELECT ROW_NUMBER() OVER (ORDER BY RN DESC) RNK, Joined
            FROM   re)
SELECT @QUERY  = 'SELECT OO.Animal_ID, OO.Name, CASE WHEN XX.REFERENCED IS NULL THEN ''No'' ELSE ''Yes'' END Referenced
FROM   Animal OO
       OUTER APPLY (SELECT SUM(1) REFERENCED
                    FROM   (' + Joined + ') II) XX'
FROM   fi
WHERE  RNK = 1

EXEC (@QUERY)


                        
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