SQL Server：如何从 information_schema 获取外键引用？

Question

在SQL Server中，如何从外键中获取引用的表+列名？

注意：不是键所在的表/列，而是它引用的键。

示例：

当表[T_ALV_Ref_FilterDisplay]中的键[FA_MDT_ID]时。 指的是 [T_AP_Ref_Customer].[MDT_ID]

例如在创建这样的约束时：

ALTER TABLE [dbo].[T_ALV_Ref_FilterDisplay]  WITH CHECK ADD  CONSTRAINT [FK_T_ALV_Ref_FilterDisplay_T_AP_Ref_Customer] FOREIGN KEY([FA_MDT_ID])
REFERENCES [dbo].[T_AP_Ref_Customer] ([MDT_ID])
GO

我需要获取 [T_AP_Ref_Customer].[MDT_ID] 当给定 [T_ALV_Ref_FilterAnzeige].[FA_MDT_ID] 作为输入时

Answer 1

没关系，这是正确的答案：
http://msdn.microsoft.com/en-us/ Library/aa175805(SQL.80).aspx

SELECT 
     KCU1.CONSTRAINT_SCHEMA AS FK_CONSTRAINT_SCHEMA 
    ,KCU1.CONSTRAINT_NAME AS FK_CONSTRAINT_NAME 
    ,KCU1.TABLE_SCHEMA AS FK_TABLE_SCHEMA 
    ,KCU1.TABLE_NAME AS FK_TABLE_NAME 
    ,KCU1.COLUMN_NAME AS FK_COLUMN_NAME 
    ,KCU1.ORDINAL_POSITION AS FK_ORDINAL_POSITION 
    ,KCU2.CONSTRAINT_SCHEMA AS REFERENCED_CONSTRAINT_SCHEMA 
    ,KCU2.CONSTRAINT_NAME AS REFERENCED_CONSTRAINT_NAME 
    ,KCU2.TABLE_SCHEMA AS REFERENCED_TABLE_SCHEMA 
    ,KCU2.TABLE_NAME AS REFERENCED_TABLE_NAME 
    ,KCU2.COLUMN_NAME AS REFERENCED_COLUMN_NAME 
    ,KCU2.ORDINAL_POSITION AS REFERENCED_ORDINAL_POSITION 
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS RC 

INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU1 
    ON KCU1.CONSTRAINT_CATALOG = RC.CONSTRAINT_CATALOG  
    AND KCU1.CONSTRAINT_SCHEMA = RC.CONSTRAINT_SCHEMA 
    AND KCU1.CONSTRAINT_NAME = RC.CONSTRAINT_NAME 

INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS KCU2 
    ON KCU2.CONSTRAINT_CATALOG = RC.UNIQUE_CONSTRAINT_CATALOG  
    AND KCU2.CONSTRAINT_SCHEMA = RC.UNIQUE_CONSTRAINT_SCHEMA 
    AND KCU2.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME 
    AND KCU2.ORDINAL_POSITION = KCU1.ORDINAL_POSITION 

注意：
Information_schema 不包含索引（它确实找到唯一约束）。
因此，如果您想根据唯一索引查找外键，则需要查看微软专有表：

SELECT  
     fksch.name AS FK_CONSTRAINT_SCHEMA 
    ,fk.name AS FK_CONSTRAINT_NAME 

    ,sch1.name AS FK_TABLE_SCHEMA 
    ,t1.name AS FK_TABLE_NAME 
    ,c1.name AS FK_COLUMN_NAME 
    -- The column_id is not the ordinal, it can be dropped and then there's a gap... 
    ,COLUMNPROPERTY(c1.object_id, c1.name, 'ordinal') AS FK_ORDINAL_POSITION 

    ,COALESCE(pksch.name,sch2.name) AS REFERENCED_CONSTRAINT_SCHEMA 
    ,COALESCE(pk.name, sysi.name) AS REFERENCED_CONSTRAINT_NAME 

    ,sch2.name AS REFERENCED_TABLE_SCHEMA 
    ,t2.name AS REFERENCED_TABLE_NAME 
    ,c2.name AS REFERENCED_COLUMN_NAME 
    ,COLUMNPROPERTY(c2.object_id, c2.name, 'ordinal') AS REFERENCED_ORDINAL_POSITION 
FROM sys.foreign_keys AS fk 

LEFT JOIN sys.schemas AS fksch 
    ON fksch.schema_id = fk.schema_id 

-- not inner join: unique indices 
LEFT JOIN sys.key_constraints AS pk
    ON pk.parent_object_id = fk.referenced_object_id 
    AND pk.unique_index_id = fk.key_index_id 

LEFT JOIN sys.schemas AS pksch 
    ON pksch.schema_id = pk.schema_id 

LEFT JOIN sys.indexes AS sysi 
    ON sysi.object_id = fk.referenced_object_id 
    AND sysi.index_id = fk.key_index_id 

INNER JOIN sys.foreign_key_columns AS fkc 
    ON fkc.constraint_object_id = fk.object_id 

INNER JOIN sys.tables AS t1 
    ON t1.object_id = fkc.parent_object_id 

INNER JOIN sys.schemas AS sch1 
    ON sch1.schema_id = t1.schema_id 

INNER JOIN sys.columns AS c1 
    ON c1.column_id = fkc.parent_column_id 
    AND c1.object_id = fkc.parent_object_id 

INNER JOIN sys.tables AS t2 
    ON t2.object_id = fkc.referenced_object_id 

INNER JOIN sys.schemas AS sch2 
    ON sch2.schema_id = t2.schema_id 

INNER JOIN sys.columns AS c2 
    ON c2.column_id = fkc.referenced_column_id 
    AND c2.object_id = fkc.referenced_object_id

边缘情况的证明测试：

CREATE TABLE __groups ( grp_id int, grp_name varchar(50), grp_name2 varchar(50) )
ALTER TABLE __groups ADD CONSTRAINT UQ___groups_grp_name2 UNIQUE (grp_name2)
CREATE UNIQUE INDEX IX___groups_grp_name ON __groups(grp_name)

GO
CREATE TABLE __group_mappings( map_id int, map_grp_name varchar(50), map_grp_name2 varchar(50), map_usr_name varchar(50) )
GO

ALTER TABLE __group_mappings  ADD  CONSTRAINT FK___group_mappings___groups FOREIGN KEY(map_grp_name)
REFERENCES __groups (grp_name)
GO


ALTER TABLE __group_mappings  ADD  CONSTRAINT FK___group_mappings___groups2 FOREIGN KEY(map_grp_name2)
REFERENCES __groups (grp_name2)
GO


SELECT @@VERSION -- Microsoft SQL Server 2016 (SP1-GDR) (KB4458842)
SELECT version() -- PostgreSQL 9.6.6 on x86_64-pc-linux-gnu
GO

Answer 2

如果您可以接受使用 SQL Server 特定架构目录视图，此查询将返回您正在寻找的内容：

SELECT  
    fk.name,
    OBJECT_NAME(fk.parent_object_id) 'Parent table',
    c1.name 'Parent column',
    OBJECT_NAME(fk.referenced_object_id) 'Referenced table',
    c2.name 'Referenced column'
FROM 
    sys.foreign_keys fk
INNER JOIN 
    sys.foreign_key_columns fkc ON fkc.constraint_object_id = fk.object_id
INNER JOIN
    sys.columns c1 ON fkc.parent_column_id = c1.column_id AND fkc.parent_object_id = c1.object_id
INNER JOIN
    sys.columns c2 ON fkc.referenced_column_id = c2.column_id AND fkc.referenced_object_id = c2.object_id

不确定如何 - 如果有的话 - 您可以从 INFORMATION_SCHEMA 视图中获取相同的信息....

Answer 3

我想要一个可以让我找到所有具有/缺少约束的“Key”和“ID”列的版本。所以我想要将所有列与所有 PK OR FK OR Null 的列表进行比较，这是我的查询。希望它对其他人有帮助！

SELECT 
     c.table_schema
    ,c.table_name
    ,c.column_name
    ,KeyConstraints.constraint_type
    ,KeyConstraints.constraint_schema
    ,KeyConstraints.constraint_name
    ,KeyConstraints.referenced_table_schema
    ,KeyConstraints.referenced_table_name
    ,KeyConstraints.referenced_column_name
    ,KeyConstraints.update_rule
    ,KeyConstraints.delete_rule
FROM information_schema.columns AS c 
LEFT JOIN 
    (
        SELECT 
             FK.table_schema AS TABLE_SCHEMA
            ,FK.table_name
            ,CU.column_name
            ,FK.constraint_type
            ,c.constraint_schema
            ,C.constraint_name
            ,PK.table_schema AS REFERENCED_TABLE_SCHEMA
            ,PK.table_name AS REFERENCED_TABLE_NAME
            ,CCU.column_name AS REFERENCED_COLUMN_NAME
            ,C.update_rule
            ,C.delete_rule
        FROM information_schema.referential_constraints AS C 

        INNER JOIN information_schema.table_constraints AS FK 
            ON C.constraint_name = FK.constraint_name 

        INNER JOIN information_schema.table_constraints AS PK 
            ON C.unique_constraint_name = PK.constraint_name 

        INNER JOIN information_schema.key_column_usage AS CU 
            ON C.constraint_name = CU.constraint_name 

        INNER JOIN information_schema.constraint_column_usage AS CCU 
            ON PK.constraint_name = CCU.constraint_name 

        WHERE ( FK.constraint_type = 'FOREIGN KEY' ) 

        UNION 

        SELECT 
             ccu.table_schema
            ,ccu.table_name
            ,ccu.column_name
            ,tc.constraint_type
            ,ccu.constraint_schema
            ,ccu.constraint_name
            ,NULL
            ,NULL
            ,NULL
            ,NULL
            ,NULL
        FROM information_schema.constraint_column_usage ccu 

        INNER JOIN information_schema.table_constraints tc 
            ON ccu.table_schema = tc.table_schema 
            AND ccu.table_name = tc.table_name 

        WHERE tc.constraint_type = 'PRIMARY KEY'

    ) AS KeyConstraints 
    ON c.table_schema = KeyConstraints.table_schema 
    AND c.table_name = KeyConstraints.table_name 
    AND c.column_name = KeyConstraints.column_name 

WHERE c.column_name LIKE '%ID' OR c.column_name LIKE '%Key' 
ORDER BY  c.table_schema 
         ,c.table_name 
         ,c.column_name 
; 

格式由以下内容提供：http://www.dpriver.com/pp/sqlformat.htm

Answer 4

you can use the following script in order to find all the fk,pk relationship for specific table 

    *DECLARE @tablename VARCHAR(100)
    SET @tablename='xxxxxxx'
    Select 'Referenced by FK table' AS Type,  FK.TABLE_SCHEMA, FK.TABLE_NAME AS 
    'FK_TABLE_NAME' ,cu.COLUMN_NAME AS 'FK_ReferencingColumn',PK.TABLE_NAME AS 
    'PK_TABLE_NAME',
   ku.COLUMN_NAME AS 'PK_ReferencedColumn'
    From INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS As RC
        Join INFORMATION_SCHEMA.TABLE_CONSTRAINTS As PK
            On PK.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME
        Join INFORMATION_SCHEMA.TABLE_CONSTRAINTS As FK
            On FK.CONSTRAINT_NAME = RC.CONSTRAINT_NAME
       JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE cu
       ON cu.CONSTRAINT_NAME = Rc.CONSTRAINT_NAME
         JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE ku
    ON ku.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME
    Where 
        PK.TABLE_NAME = @tablename
    UNION  
    SELECT 'Referencing PK table' AS Type, FK.TABLE_SCHEMA, FK.TABLE_NAME AS 
    'FK_TABLE_NAME' ,cu.COLUMN_NAME AS 'FK_ReferencingColumn',PK.TABLE_NAME AS 
    'PK_TABLE_NAME',
     ku.COLUMN_NAME AS 'PK_ReferencedColumn'
    From INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS As RC
        Join INFORMATION_SCHEMA.TABLE_CONSTRAINTS As PK
            On PK.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME
        Join INFORMATION_SCHEMA.TABLE_CONSTRAINTS As FK
            On FK.CONSTRAINT_NAME = RC.CONSTRAINT_NAME
       JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE cu
       ON cu.CONSTRAINT_NAME = Rc.CONSTRAINT_NAME
         JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE ku
    ON ku.CONSTRAINT_NAME = RC.UNIQUE_CONSTRAINT_NAME
   Where 
        fk.TABLE_NAME = @tablename*