如何在Microsoft SQL中删除约束表？

Question

我怎样才能删除表与约束，

use my_db0 


if exists(select* from sys.tables where name='Tbl1') 
drop table Tbl1 --cascade constraints; 


Create table Tbl1(
nameID int primary key 
) 


if exists (select* from sys.tables where name='Tbl2') 
drop table Tbl2 


Create table Tbl2(
lastNameID int primary key, 
nameID int foreign key references Tbl1(nameID) 
) 

Answer 1

您可以使用此查询：

Select Query = 
    'If EXISTS (Select * FROM sys.foreign_keys Where ' 
     + ' object_id = OBJECT_ID(N''' + QUOTENAME(OBJECT_SCHEMA_NAME(fk.parent_object_id)) + '.' + QUOTENAME(fk.name) + ''')' 
     + ' And parent_object_id = OBJECT_ID(N''' + QUOTENAME(OBJECT_SCHEMA_NAME(fk.parent_object_id)) + '.' + OBJECT_NAME(fk.parent_object_id) + ''')) ' + 

    'ALTER TABLE ' + QUOTENAME(OBJECT_SCHEMA_NAME(fk.parent_object_id)) 
     + '.' + QUOTENAME(OBJECT_NAME(fk.parent_object_id)) 
     + ' DROP CONSTRAINT ' + QUOTENAME(fk.name) + '; ' 
    , [Schema] = sh.name, [Table] = OBJECT_NAME(fk.parent_object_id), [Constraint] = ob.name 

From sys.foreign_keys as fk 
Inner Join sys.objects as ob on ob.object_id = fk.parent_object_id 
Inner Join sys.schemas as sh on ob.schema_id = sh.schema_id 
Where ob.name in ('xxx', 'yyy'); 

这将输出：

• 跌落约束查询
• 架构名称
• 表名
• 约束名

然后，您可以dynamicaly在第一列执行查询：

Exec sp_executesql @sql 

凡@sql来自查询列。一旦约束条件被删除，您可以删除表格。

Answer 2

表TBL2包含填充NameID作为外键，所以你必须先擦拭的数据TBL2，然后删除TBL1

if exists (select* from sys.tables where name='Tbl2') 
drop table Tbl2 

if exists(select* from sys.tables where name='Tbl1') 
drop table Tbl1 

Answer 3

在SQL Server 2016，你可以使用DROP IF EXISTS：

ALTER TABLE my_table 
DROP CONSTRAINT IF EXISTS <name> 

DROP TABLE IF EXISTS my_table 

见http://blogs.msdn.com/b/sqlserverstorageengine/archive/2015/11/03/drop-if-exists-new-thing-in-sql-server-2016.aspx

约万