我需要在SQL Server数据库中删除一个高度引用的表。我如何才能得到所有外键约束的列表,我将需要删除以便删除表?
(SQL比在管理工作室的GUI中点击更可取)
我需要在SQL Server数据库中删除一个高度引用的表。我如何才能得到所有外键约束的列表,我将需要删除以便删除表?
(SQL比在管理工作室的GUI中点击更可取)
当前回答
下面是我将使用的SQL代码。
SELECT
f.name AS 'Name of Foreign Key',
OBJECT_NAME(f.parent_object_id) AS 'Table name',
COL_NAME(fc.parent_object_id,fc.parent_column_id) AS 'Fieldname',
OBJECT_NAME(t.object_id) AS 'References Table name',
COL_NAME(t.object_id,fc.referenced_column_id) AS 'References fieldname',
'ALTER TABLE [' + OBJECT_NAME(f.parent_object_id) + '] DROP CONSTRAINT [' + f.name + ']' AS 'Delete foreign key',
'ALTER TABLE [' + OBJECT_NAME(f.parent_object_id) + '] WITH NOCHECK ADD CONSTRAINT [' +
f.name + '] FOREIGN KEY([' + COL_NAME(fc.parent_object_id,fc.parent_column_id) + ']) REFERENCES ' +
'[' + OBJECT_NAME(t.object_id) + '] ([' +
COL_NAME(t.object_id,fc.referenced_column_id) + '])' AS 'Create foreign key'
-- , delete_referential_action_desc AS 'UsesCascadeDelete'
FROM sys.foreign_keys AS f,
sys.foreign_key_columns AS fc,
sys.tables t
WHERE f.OBJECT_ID = fc.constraint_object_id
AND t.OBJECT_ID = fc.referenced_object_id
AND OBJECT_NAME(t.object_id) = 'Employees' -- Just show the FKs which reference a particular table
ORDER BY 2
这不是特别清晰的SQL,所以让我们看一个例子。
所以,假设我想删除Microsoft心爱的Northwind数据库中的Employees表,但是SQL Server告诉我一个或多个外键阻止我这样做。
上面的SQL命令将返回这些结果…
它显示有3个外键引用雇员表。换句话说,除非先删除这三个外键,否则不允许删除(删除)这个表。
在结果中,第一行是以下外键约束在结果中的显示方式。
ALTER TABLE [dbo].[Employees] WITH NOCHECK
ADD CONSTRAINT [FK_Employees_Employees] FOREIGN KEY([ReportsTo])
REFERENCES [dbo].[Employees] ([EmployeeID])
倒数第二列显示了我需要使用的SQL命令来删除这些外键之一,例如:
ALTER TABLE [Employees] DROP CONSTRAINT [FK_Employees_Employees]
...右边一列显示了创建它的SQL…
ALTER TABLE [Employees] WITH NOCHECK
ADD CONSTRAINT [FK_Employees_Employees]
FOREIGN KEY([ReportsTo]) REFERENCES [Employees] ([EmployeeID])
使用所有这些命令,您就拥有了删除相关外键所需的一切,从而可以删除表,然后再重新创建它们。
唷。希望这能有所帮助。
其他回答
试试这个:
sp_help 'TableName'
也试一试。
EXEC sp_fkeys 'tableName', 'schemaName'
使用sp_fkeys,不仅可以通过pk表名和模式过滤结果,还可以通过fk表名和模式过滤结果。链接
我将使用SQL Server Management Studio中的数据库图表功能,但既然你排除了它-这在SQL Server 2008中为我工作(没有2005)。
获取引用表和列名的列表…
select
t.name as TableWithForeignKey,
fk.constraint_column_id as FK_PartNo, c.
name as ForeignKeyColumn
from
sys.foreign_key_columns as fk
inner join
sys.tables as t on fk.parent_object_id = t.object_id
inner join
sys.columns as c on fk.parent_object_id = c.object_id and fk.parent_column_id = c.column_id
where
fk.referenced_object_id = (select object_id
from sys.tables
where name = 'TableOthersForeignKeyInto')
order by
TableWithForeignKey, FK_PartNo
获取外键约束的名称
select distinct name from sys.objects where object_id in
( select fk.constraint_object_id from sys.foreign_key_columns as fk
where fk.referenced_object_id =
(select object_id from sys.tables where name = 'TableOthersForeignKeyInto')
)
SELECT
OBJECT_NAME(parent_object_id) 'Parent table',
c.NAME 'Parent column name',
OBJECT_NAME(referenced_object_id) 'Referenced table',
cref.NAME 'Referenced column name'
FROM
sys.foreign_key_columns fkc
INNER JOIN
sys.columns c
ON fkc.parent_column_id = c.column_id
AND fkc.parent_object_id = c.object_id
INNER JOIN
sys.columns cref
ON fkc.referenced_column_id = cref.column_id
AND fkc.referenced_object_id = cref.object_id where OBJECT_NAME(parent_object_id) = 'tablename'
如果你想获得所有表的外键关系,排除where子句,否则写你的tablename而不是tablename
SELECT PKTABLE_QUALIFIER = CONVERT(SYSNAME,DB_NAME()),
PKTABLE_OWNER = CONVERT(SYSNAME,SCHEMA_NAME(O1.SCHEMA_ID)),
PKTABLE_NAME = CONVERT(SYSNAME,O1.NAME),
PKCOLUMN_NAME = CONVERT(SYSNAME,C1.NAME),
FKTABLE_QUALIFIER = CONVERT(SYSNAME,DB_NAME()),
FKTABLE_OWNER = CONVERT(SYSNAME,SCHEMA_NAME(O2.SCHEMA_ID)),
FKTABLE_NAME = CONVERT(SYSNAME,O2.NAME),
FKCOLUMN_NAME = CONVERT(SYSNAME,C2.NAME),
-- Force the column to be non-nullable (see SQL BU 325751)
--KEY_SEQ = isnull(convert(smallint,k.constraint_column_id), sysconv(smallint,0)),
UPDATE_RULE = CONVERT(SMALLINT,CASE OBJECTPROPERTY(F.OBJECT_ID,'CnstIsUpdateCascade')
WHEN 1 THEN 0
ELSE 1
END),
DELETE_RULE = CONVERT(SMALLINT,CASE OBJECTPROPERTY(F.OBJECT_ID,'CnstIsDeleteCascade')
WHEN 1 THEN 0
ELSE 1
END),
FK_NAME = CONVERT(SYSNAME,OBJECT_NAME(F.OBJECT_ID)),
PK_NAME = CONVERT(SYSNAME,I.NAME),
DEFERRABILITY = CONVERT(SMALLINT,7) -- SQL_NOT_DEFERRABLE
FROM SYS.ALL_OBJECTS O1,
SYS.ALL_OBJECTS O2,
SYS.ALL_COLUMNS C1,
SYS.ALL_COLUMNS C2,
SYS.FOREIGN_KEYS F
INNER JOIN SYS.FOREIGN_KEY_COLUMNS K
ON (K.CONSTRAINT_OBJECT_ID = F.OBJECT_ID)
INNER JOIN SYS.INDEXES I
ON (F.REFERENCED_OBJECT_ID = I.OBJECT_ID
AND F.KEY_INDEX_ID = I.INDEX_ID)
WHERE O1.OBJECT_ID = F.REFERENCED_OBJECT_ID
AND O2.OBJECT_ID = F.PARENT_OBJECT_ID
AND C1.OBJECT_ID = F.REFERENCED_OBJECT_ID
AND C2.OBJECT_ID = F.PARENT_OBJECT_ID
AND C1.COLUMN_ID = K.REFERENCED_COLUMN_ID
AND C2.COLUMN_ID = K.PARENT_COLUMN_ID