sql取不为空的列
一条记录有的列为空，我如何select 列1，列2,这些不为空的列，为空的不在select 中
[解决办法]
create table tbA
(col1 int,col2 int,col3 int,col4 int)
insert tbA
select 1,2,3,null union all
select 1,2,3,null union all
select 1,2,null,null union all
select 1,2,3,null union all
select 1,2,3,null union all
select 1,2,3,null
go
--col1和col2没有空值
declare @sql as nvarchar(4000)
set @sql=''
select @sql=@sql+'+case when not exists(select 1 from tbA where '+[name]+' is null) then '',' +[name]+''' else '''' end'
from sys.columns where [object_id]=object_id('tbA')
set @sql=' declare @sql2 as nvarchar(4000)'+
' set @sql2= '+stuff(@sql,1,1,'')+
' set @sql2=stuff(@sql2,1,1,'''') '+
' exec(''select ''+ @sql2+'' from tbA'')'
exec(@sql)
col1 col2
----------- -----------
1 2
1 2
1 2
1 2
1 2
1 2
(6 row(s) affected)
go
--col1、col2、col3不全为空
declare @sql as nvarchar(4000)
set @sql=''
select @sql=@sql+'+case when exists(select 1 from tbA where '+[name]+' is not null) then '',' +[name]+''' else '''' end'
from sys.columns where [object_id]=object_id('tbA')
set @sql=' declare @sql2 as nvarchar(4000)'+
' set @sql2= '+stuff(@sql,1,1,'')+
' set @sql2=stuff(@sql2,1,1,'''') '+
' exec(''select ''+ @sql2+'' from tbA'')'
exec(@sql)
col1 col2 col3
----------- ----------- -----------
1 2 3
1 2 3
1 2 NULL
1 2 3
1 2 3
1 2 3
(6 row(s) affected)
--显示非零列
--考勤奖全为null则不显示
create table a(a int,b int,c int)
insert a
select 1,2,NULL
declare @sql nvarchar(4000)
declare @var nvarchar(4000)
select @sql=isnull(@sql+'+','')+'case when exists(select 1 from a where '+[name]+' is not null) then '
+quotename(','+name,'''')+' else '''' end '
from syscolumns where id=object_id('a')
set @sql='select @a='+@sql+' from a '
exec sp_executesql @sql,N'@a varchar(4000) output',@var output
set @sql='select '+stuff(@var,1,1,'')+' from a'
exec(@sql)
drop table a
/*
a b
----------- -----------
1 2
*/
