原来的数据库有好多类型的数据默认值都是 null 值，为以后在实际开发过程中带了好多不变。这个null其实也有好处，我想可以节省数据库的空间，在新增数据的时候还可以提高速度。不过还是应领导要求写了下面的代码。在CSDN的大侠帮助下完成的。
declare @t table(id int identity(1,1),tbname varchar(256), colname varchar(256),xtype varchar(20))
insert into @t
select a.name,b.name ,c.name
from sysobjects a
inner join syscolumns b on a.id=b.id
inner join systypes c on b.xusertype = c.xusertype
where a.xtype="u"
and c.name in ("varchar","int")
and b.status<>0x80 --去掉自增列
and not exists --过滤掉原来已存在默认值的列
(select 1
from
(select
(select name from sysobjects where id=c.id) 表名,
(select name from syscolumns where cdefault=a.id) 字段名
from sysobjects b,syscolumns c,syscomments a
where b.xtype="d"
and a.id=b.id
and b.parent_obj=c.id
and a.colid=c.colid
) t
where a.name=t.表名
and b.name=t.字段名)
--select * from @t
declare @i int
set @i=1
declare @tbname varchar(256),@colname varchar(256),@xtype varchar(20),@sql nvarchar(4000)
while @i <= (select MAX(id) from @t)
begin
select @tbname=tbname,@colname=colname,@xtype = xtype from @t where id=@i
set @sql = "alter table ["+@tbname+"] add constraint " + "df_" + replace(@tbname,"-","") +"_"+ replace(@colname,"-","") + " default "
if @xtype = "int"
begin
set @sql = @sql + " 0 "
end
else if @xtype = "varchar"
begin
set @sql = @sql + """"""
end
set @sql = @sql + " for [" + @colname +"]"
exec(@sql)
set @i = @i + 1
end
小记
注册好以后基本就没有来过，以后会把自己学习的点点都记在这边。记录自己成长。