改int非空自增列为int可为空列

declare @TableName nvarchar(250)
--声明读取数据库所有数据表名称游标mycursor1
declare mycursor1 cursor for select name from dbo.SysObjects WHERE OBJECTPROPERTY(ID, 'IsUserTable') = 1
open mycursor1 
--从游标里取出数据赋值到我们刚才声明的数据表名变量中
fetch next from mycursor1 into @TableName 
--如果游标执行成功  
while (@@fetch_status=0)
begin 
--声明读取数据表中所有int 不能为空 的字段 名称游标mycursor2
    declare @ColumnName nvarchar(250)
    --要修改的自增列 
    declare mycursor2 cursor for select name from syscolumns Where ID=OBJECT_ID(N'['+@TableName+']') and name like ('%id%') and xtype=56 and isnullable=0
    --打开游标    
    open mycursor2 
    --从游标里取出数据赋值到我们刚才声明的数据字段变量中
    fetch next from mycursor2 into @ColumnName
    IF (CURSOR_STATUS('global','mycursor2')=1 )--游标的结果集至少有一行
    begin
    --如果游标执行成功 
    while (@@fetch_status=0)    
    begin
        --新增一列，把自增列值赋给新增列,删除自增列，修改改列名
        exec('alter table ['+@TableName+'] add temp_id int null')
        exec('update [DB_zabnew].[dbo].[zab_chaKan] set temp_id='+@ColumnName+'')
        exec('alter table ['+@TableName+'] drop column '+@ColumnName+'')
        exec sp_rename ''+@TableName+'.ck_id_id',@ColumnName,'column'    
        --自己原来的做法，这样新加的列中就没有数据了。
        --先把自增列删除
        --exec ('ALTER TABLE ['+@TableName+'] DROP COLUMN '+@ColumnName+'')
        --再添加非自增列
        --exec ('ALTER TABLE ['+@TableName+'] alter column '+@ColumnName+' [int] NULL') 
        fetch next from mycursor2 into @ColumnName
        end
    end
    --关闭游标
    close mycursor2
    --撤销游标
    deallocate mycursor2
 --用游标去取下一条记录
 fetch next from mycursor1 into @TableName
end 
--关闭游标
close mycursor1
--撤销游标
deallocate mycursor1