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
我知道这是一个很晚(非常晚)的回复,但我找到了这些简单的方法来找到所有的foreign_key_references。这是解决方案;
解决方案1:
EXEC SP_FKEYS 'MyTableName'; // It'll show you the all the information(in multiple tables) regarding to the TableName with all ForeignKey_References.
解决方案2:
EXEC SP_HELP 'MyTableName'; // It'll show all ForeignKey references in a single table.
解决方案03:
// It'll show you the Column_Name with Referenced_Table_Name
SELECT
COL_NAME(fc.parent_object_id,fc.parent_column_id) Column_Name,
OBJECT_NAME(f.parent_object_id) Table_Name
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.tables t
ON t.OBJECT_ID = fc.referenced_object_id
WHERE
OBJECT_NAME (f.referenced_object_id) = 'MyTableName'
希望这对你有很大帮助。: -)
其他回答
with tab_list as (
select t.name AS Table_Name, t.object_id, s.name AS Table_Schema from sys.tables t, sys.schemas s
where t.schema_id = s.schema_id
and s.name = 'your schema')
select IIF(col.column_id = 1, tab.TABLE_SCHEMA + '.' + tab.TABLE_NAME, NULL) Table_Name,
col.Name AS Column_Name, IIF(col.IS_NULLABLE= 0, 'NOT NULL', '') Nullable, st.name Type,
CASE WHEN st.name = 'decimal' THEN CONVERT(NVARCHAR(4000), col.Precision) + ',' + CONVERT(NVARCHAR(4000), col.Scale)
WHEN col.max_length = -1 THEN 'max'
WHEN st.name in ('int', 'bit', 'bigint', 'datetime2') THEN NULL
ELSE CONVERT(NVARCHAR(4000), col.max_length / 2)
END
AS Length,
ss.name + '.' + stab.name Referenced_Table, scol.name Referenced_Column
from sys.COLUMNS col
INNER JOIN tab_list tab ON col.object_id = tab.object_id
INNER JOIN sys.types st ON col.system_type_id = st.system_type_id AND col.user_type_id = st.user_type_id
LEFT JOIN [sys].[foreign_key_columns] sfkc ON col.object_id = sfkc.parent_object_id AND col.column_id = sfkc.parent_column_id
LEFT JOIN sys.tables stab ON sfkc.referenced_object_id = stab.object_id
LEFT JOIN sys.columns scol ON sfkc.referenced_object_id = scol.object_id AND sfkc.referenced_column_id = scol.column_id
LEFT JOIN sys.schemas ss ON ss.schema_id = stab.schema_id
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。
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
Oracle SQL
select *
from
all_constraints
where
r_constraint_name in
(select constraint_name
from
all_constraints
where
table_name='PUT_THE_TABLE_NAME_HERE');
all_constraints是Oracle DB中的一个固有表名。
不知道为什么没有人建议,但我使用sp_fkeys查询给定表的外键:
EXEC sp_fkeys 'TableName'
你也可以指定模式:
EXEC sp_fkeys @pktable_name = 'TableName', @pktable_owner = 'dbo'
在没有指定模式的情况下,文档声明如下:
如果没有指定pktable_owner,则默认表可见性规则 的基础DBMS应用程序。 在SQL Server中,如果当前用户拥有一个具有指定 Name,返回该表的列。如果pktable_owner不是 且当前用户不拥有具有指定属性的表 Pktable_name时,该过程查找具有指定 由数据库所有者拥有的Pktable_name。如果存在,那张桌子就是 返回列。