在FK中查找目標列

Question

如果我有一對SQL表，其中一個表在一列上具有pk，在另一列上具有唯一索引（可能是guid和id或某個其他唯一鍵）。

另一個表具有唯一索引的fk，而不是pk。有沒有一種方法可以查詢信息模式以查找fk所針對的列？

Answer 1

如果我得到你的權利，你要使用元數據庫：

SELECT 
K_Table = FK.TABLE_NAME, 
FK_Column = CU.COLUMN_NAME, 
PK_Table = PK.TABLE_NAME, 
PK_Column = PT.COLUMN_NAME, 
Constraint_Name = C.CONSTRAINT_NAME 
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS C 
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS FK ON C.CONSTRAINT_NAME = FK.CONSTRAINT_NAME 
INNER JOIN INFORMATION_SCHEMA.TABLE_CONSTRAINTS PK ON C.UNIQUE_CONSTRAINT_NAME = PK.CONSTRAINT_NAME 
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU ON C.CONSTRAINT_NAME = CU.CONSTRAINT_NAME 
INNER JOIN (
SELECT i1.TABLE_NAME, i2.COLUMN_NAME 
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS i1 
INNER JOIN INFORMATION_SCHEMA.KEY_COLUMN_USAGE i2 ON i1.CONSTRAINT_NAME = i2.CONSTRAINT_NAME 
WHERE i1.CONSTRAINT_TYPE = 'PRIMARY KEY' 
) PT ON PT.TABLE_NAME = PK.TABLE_NAME 

來源：http://blog.sqlauthority.com/2006/11/01/sql-server-query-to-display-foreign-key-relationships-and-name-of-the-constraint-for-each-table-in-database/

Answer 2

嘗試這一個 -

SELECT 
     column_name = c.name 
    , table_name = OBJECT_NAME(k.parent_object_id) 
    , referenced_column_name = rc.name 
    , referenced_table_name = OBJECT_NAME(k.referenced_object_id) 
FROM sys.foreign_key_columns k 
JOIN sys.columns c ON c.[object_id] = k.parent_object_id AND c.column_id = k.parent_column_id 
JOIN sys.columns rc ON rc.[object_id] = k.referenced_object_id AND rc.column_id = k.referenced_column_id 

Answer 3

--FIND列，其主鍵好的外鍵 - SQL SERVER 2008

SELECT 
CU.TABLE_NAME, CU.COLUMN_NAME 
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE CU 
WHERE CU.CONSTRAINT_NAME IN (SELECT CONSTRAINT_NAME FROM   INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
WHERE CONSTRAINT_TYPE = 'PRIMARY KEY') AND 
COLUMN_NAME IN (SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE 
WHERE TABLE_NAME = CU.TABLE_NAME AND 
COLUMN_NAME = CU.COLUMN_NAME AND 
CONSTRAINT_NAME IN (SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
WHERE CONSTRAINT_TYPE = 'FOREIGN KEY')) 

來源：here

Answer 4

select object_name(fk.REFERENCED_OBJECT_ID) object_name, 
     i.name index_name, 
     ic.index_column_id sequence, 
     c.name column_name 
    from sys.foreign_keys fk 
    join sys.indexes i on i.object_id = fk.REFERENCED_OBJECT_ID 
        and i.index_id = fk.KEY_INDEX_ID 
    join sys.index_columns ic on ic.object_id = fk.REFERENCED_OBJECT_ID 
          and ic.index_id = fk.KEY_INDEX_ID 
    join sys.columns c on c.object_id = fk.REFERENCED_OBJECT_ID 
        and c.column_id = ic.column_id 
where fk.name = 'fk_tbl2_to_tbl1'; 

例如

設置：

create table tbl1 (
    a int constraint pk_tbl1 primary key, 
    b int constraint uq_tbl1 unique, 
    c int); 
create table tbl2 (
    b int constraint fk_tbl2_to_tbl1 references tbl1(b), 
    d int); 

結果：

| OBJECT_NAME | INDEX_NAME | SEQUENCE | COLUMN_NAME | 
----------------------------------------------------- 
|  tbl1 | uq_tbl1 |  1 |   b | 

SQL Fiddle Demo