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

第一个

EXEC sp_fkeys 'Table', 'Schema'

然后使用NimbleText处理你的结果

@BankZ的最好回答

sp_help 'TableName'   

另外,对于不同的模式

sp_help 'schemaName.TableName'   

您还应该注意对其他对象的引用。

如果表被其他表高度引用,那么它也可能被其他对象(如视图、存储过程、函数等)高度引用。

我真的推荐GUI工具,如SSMS中的“查看依赖关系”对话框或免费工具,如ApexSQL Search,因为如果你只想用SQL来搜索其他对象的依赖关系,可能会出错。

如果SQL是唯一的选择,您可以尝试这样做。

select O.name as [Object_Name], C.text as [Object_Definition]
from sys.syscomments C
inner join sys.all_objects O ON C.id = O.object_id
where C.text like '%table_name%'

SQL Server中所有引用给定表的外键列表:

您可以通过以下查询获得引用表名和列名…

SELECT 
   OBJECT_NAME(f.parent_object_id) TableName,
   COL_NAME(fc.parent_object_id,fc.parent_column_id) ColName
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) = 'TableName'

下面的截图让你理解…

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