unamed 기본 값 제약 조건 및 알 수없는 인덱스가있는 열을 삭제하는 방법

Question

열과 이름에 기본 제약 조건이 있는지, 그리고 삭제하기 전에 삭제할 인덱스의 이름을 결정하는 방법은 무엇입니까? 칼럼?

Answer 1

다음 유틸리티 procs가 작업을 수행합니다. 우리가 사용하지 않는 내가 외래 키 제약 조건에보고하지 않은

exec [dbo]._spDropColumn 'TableName', 'ColumnName' 

, 그러나 아마 그들도 포함될 수 :

if (exists (select * from [dbo].sysobjects where (id = object_id(N'[dbo]._spDropDefaultValueConstraint')) and (xtype = 'P'))) 
drop procedure [dbo]._spDropDefaultValueConstraint 
GO 

create procedure [dbo]._spDropDefaultValueConstraint 
@TableName varchar(256), 
@ColumnName varchar(256) 
as 
/* This proc will drop the default value constraint on 
a column even when you don't know what its name is. 
*/ 
declare @ConstraintName varchar(256) 
set @ConstraintName = (
select 
    dobj.name 
from sys.columns col 
    left outer join sys.objects dobj 
    on dobj.object_id = col.default_object_id and dobj.type = 'D' 
where col.object_id = object_id('[dbo].'+@TableName) 
and dobj.name is not null 
and col.name = @ColumnName) 

if(isnull(@ConstraintName, '') <> '') 
exec('alter table [dbo].['+@TableName+'] drop constraint ['+@ConstraintName+']') 

GO 

------------------------------------------------------------------------------------------- 

if (exists (select * from [dbo].sysobjects where (id = object_id(N'[dbo]._spDropIndexesForColumn')) and (xtype = 'P'))) 
drop procedure [dbo]._spDropIndexesForColumn 
GO 

create procedure [dbo]._spDropIndexesForColumn 
@TableName varchar(256), 
@ColumnName varchar(256) 
as 
/* This proc will drop all indexes on a column, both indexes 
and unique constraints as well as multi-part indexes that reference it. 
*/ 
declare @IndexName varchar(256) 
declare @IsPrimaryKey bit 
declare @IsUniqueConstraint bit 

declare crIndexes cursor for 
select 
    ind.name, ind.is_primary_key, ind.is_unique_constraint 
from 
    sys.indexes ind 
    inner join sys.index_columns ic on ind.object_id = ic.object_id and ind.index_id = ic.index_id 
    inner join sys.columns col on ic.object_id = col.object_id and ic.column_id = col.column_id 
    inner join sys.tables t on ind.object_id = t.object_id 
where 
    t.name = @TableName and 
    col.name = @ColumnName  
open crIndexes 
fetch next from crIndexes into @IndexName, @IsPrimaryKey, @IsUniqueConstraint 
while(@@fetch_status = 0) begin 
if(@IsPrimaryKey = 1) or (@IsUniqueConstraint = 1) 
    exec('alter table [dbo].['+@TableName+'] drop constraint ['+@IndexName+']') 
else 
    exec('drop index [dbo].['+@TableName+'].['+@IndexName+']') 
fetch next from crIndexes into @IndexName, @IsPrimaryKey, @IsUniqueConstraint 
end 
close crIndexes 
deallocate crIndexes 

GO 

------------------------------------------------------------------------------------------- 

if (exists (select * from [dbo].sysobjects where (id = object_id(N'[dbo]._spDropColumn')) and (xtype = 'P'))) 
drop procedure [dbo]._spDropColumn 
GO 

create procedure [dbo]._spDropColumn 
@TableName varchar(256), 
@ColumnName varchar(256) 
as 
/* This proc will drop a column (first dropping the default value 
constraint and any indexes if they exist) if it exists. 
*/ 
if (exists (select * from [dbo].sysobjects where (id = object_id('[dbo].'+@TableName)) and (xtype = 'U'))) and 
    (exists (select * from [dbo].syscolumns where (id = object_id('[dbo].'+@TableName)) and (name = @ColumnName))) begin 
exec [dbo]._spDropIndexesForColumn @TableName, @ColumnName 
exec [dbo]._spDropDefaultValueConstraint @TableName, @ColumnName 
exec('alter table [dbo].['+@TableName+'] drop column ['+@ColumnName+']') 
end 
GO 

은 다음과 같이 호출 다음 쉽다.