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
上面有一些不错的答案。但我更喜欢一个问题就能得到答案。 这段代码来自sys. .Sp_helpconstraint (sys proc)
这是微软查找是否有与tbl关联的外键的方法。
--setup variables. Just change 'Customer' to tbl you want
declare @objid int,
@objname nvarchar(776)
select @objname = 'Customer'
select @objid = object_id(@objname)
if exists (select * from sys.foreign_keys where referenced_object_id = @objid)
select 'Table is referenced by foreign key' =
db_name() + '.'
+ rtrim(schema_name(ObjectProperty(parent_object_id,'schemaid')))
+ '.' + object_name(parent_object_id)
+ ': ' + object_name(object_id)
from sys.foreign_keys
where referenced_object_id = @objid
order by 1
答案看起来像这样:test_db_name.dbo。账户:FK_Account_Customer
其他回答
试试这个:
sp_help 'TableName'
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')
)
@BankZ的最好回答
sp_help 'TableName'
另外,对于不同的模式
sp_help 'schemaName.TableName'
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。
最初的问题要求将所有外键的列表放入一个高度引用的表中,以便可以删除表。
这个小查询返回将所有外键放入特定表所需的“drop foreign key”命令:
SELECT
'ALTER TABLE ['+sch.name+'].['+referencingTable.Name+'] DROP CONSTRAINT ['+foreignKey.name+']' '[DropCommand]'
FROM sys.foreign_key_columns fk
JOIN sys.tables referencingTable ON fk.parent_object_id = referencingTable.object_id
JOIN sys.schemas sch ON referencingTable.schema_id = sch.schema_id
JOIN sys.objects foreignKey ON foreignKey.object_id = fk.constraint_object_id
JOIN sys.tables referencedTable ON fk.referenced_object_id = referencedTable.object_id
WHERE referencedTable.name = 'MyTableName'
示例输出:
[DropCommand]
ALTER TABLE [dbo].[OtherTable1] DROP CONSTRAINT [FK_OtherTable1_MyTable]
ALTER TABLE [dbo].[OtherTable2] DROP CONSTRAINT [FK_OtherTable2_MyTable]
省略where -子句以获取当前数据库中所有外键的删除命令。