我需要在SQL Server数据库中删除一个被大量引用的表格。我该如何获取需要删除的所有外键约束列表,以便删除该表?
(最好使用SQL语句来回答,不要在管理工作室的GUI中点击)
我需要在SQL Server数据库中删除一个被大量引用的表格。我该如何获取需要删除的所有外键约束列表,以便删除该表?
(最好使用SQL语句来回答,不要在管理工作室的GUI中点击)
不确定为什么没有人提出建议,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(schema):
EXEC sp_fkeys @pktable_name = 'TableName', @pktable_owner = 'dbo'
在未指定模式的情况下,文档中说明如下:
如果未指定pktable_owner,则使用底层DBMS的默认表可见性规则。
在SQL Server中,如果当前用户拥有指定名称的表,则返回该表的列。如果未指定pktable_owner且当前用户没有拥有指定pktable_name的表,则该过程将查找由数据库所有者拥有的具有指定pktable_name的表。如果存在这样的表,则返回该表的列。
这个给你:
以下是代码:
SELECT obj.name AS FK_NAME,
sch.name AS [schema_name],
tab1.name AS [table],
col1.name AS [column],
tab2.name AS [referenced_table],
col2.name AS [referenced_column]
FROM sys.foreign_key_columns fkc
INNER JOIN sys.objects obj
ON obj.object_id = fkc.constraint_object_id
INNER JOIN sys.tables tab1
ON tab1.object_id = fkc.parent_object_id
INNER JOIN sys.schemas sch
ON tab1.schema_id = sch.schema_id
INNER JOIN sys.columns col1
ON col1.column_id = parent_column_id AND col1.object_id = tab1.object_id
INNER JOIN sys.tables tab2
ON tab2.object_id = fkc.referenced_object_id
INNER JOIN sys.columns col2
ON col2.column_id = referenced_column_id AND col2.object_id = tab2.object_id
order by
:KeyTableSchemaName,KeyTableName,KeyColumnName,FkTableSchemaName,FkTableName,FkName,并且f)将列顺序更改为:KeyTableSchemaName,KeyTableName,KeyColumnName,FkTableSchemaName,FkTableName,FkName,FkColumnName,以保持一致性/最常见的最佳实践命名约定和d/e以实现最可能的使用(列出“表”的FK依赖项)。那就更好了。 - Tom我会建议使用SQL Server Management Studio中的数据库图形化功能,但是既然您排除了这个选项 - 在SQL Server 2008中,以下方法对我有效(我没有使用2005)。
要获取引用表和列名称的列表...
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
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')
)
试试这个:
sp_help 'TableName'
您还需要注意其他对象对该表的引用。
如果其他表高度引用了该表,则其他对象(例如视图、存储过程、函数等)对其的引用也很可能很高。
我强烈建议使用GUI工具,例如SSMS中的“查看依赖关系”对话框或免费工具ApexSQL Search,因为如果您想仅使用SQL搜索依赖项,则可能会出现错误。
如果SQL是唯一选项,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%'
原始问题要求获取所有指向高度引用表的外键列表,以便可以删除该表。
这个小查询将返回删除特定表中所有外键所需的所有“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。
最简单的方法是使用SQL中的sys.foreign_keys_columns。表格包含了所有外键的对象ID以及它们关联的列ID,参考表ID以及引用列和表。由于ID保持不变,因此结果在进一步修改模式和表时将是可靠的。
查询:
SELECT
OBJECT_NAME(fkeys.constraint_object_id) foreign_key_name
,OBJECT_NAME(fkeys.parent_object_id) referencing_table_name
,COL_NAME(fkeys.parent_object_id, fkeys.parent_column_id) referencing_column_name
,OBJECT_SCHEMA_NAME(fkeys.parent_object_id) referencing_schema_name
,OBJECT_NAME (fkeys.referenced_object_id) referenced_table_name
,COL_NAME(fkeys.referenced_object_id, fkeys.referenced_column_id)
referenced_column_name
,OBJECT_SCHEMA_NAME(fkeys.referenced_object_id) referenced_schema_name
FROM sys.foreign_key_columns AS fkeys
我们也可以使用“where”来添加过滤器
WHERE OBJECT_NAME(fkeys.parent_object_id) = 'table_name' AND
OBJECT_SCHEMA_NAME(fkeys.parent_object_id) = 'schema_name'
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
这段内容涉及到IT技术,讲解SQL语言。如果我想在微软喜爱的Northwind数据库中删除Employees表,但是SQL Server告诉我有一个或多个外键阻止了我这样做,那么下面的SQL命令将返回以下结果...
它告诉我有3个外键引用了Employees表。换句话说,在删除这个表之前,必须先删除这三个外键。
结果中,第一行是如何显示以下外键约束的结果。
ALTER TABLE [dbo].[Employees] WITH NOCHECK
ADD CONSTRAINT [FK_Employees_Employees] FOREIGN KEY([ReportsTo])
REFERENCES [dbo].[Employees] ([EmployeeID])
ALTER TABLE [Employees] DROP CONSTRAINT [FK_Employees_Employees]
...右侧列显示创建它的SQL语句...
ALTER TABLE [Employees] WITH NOCHECK
ADD CONSTRAINT [FK_Employees_Employees]
FOREIGN KEY([ReportsTo]) REFERENCES [Employees] ([EmployeeID])
使用这些命令,你可以删除相关的外键以允许你删除一个表,然后稍后重新创建它们。
哎呀,希望这能帮到你。
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
SELECT
object_name(parent_object_id),
object_name(referenced_object_id),
name
FROM sys.foreign_keys
WHERE parent_object_id = object_id('Table Name')