SET NULLDISPLAY 命令为空值(NULL) 指定显示时对应的文本
　上述此命令当生成新库时还是出现.null.
set unll off
selt SET NULLDISPLAY  to " "
select a.*,b.* from bmk as a,cjk as b where a.xh=b.xh 时　没有unll 均为空格
但当如下命令时：
set unll off
selt SET NULLDISPLAY  to " "
select a.*,b.* from bmk as a,cjk as b where a.xh=b.xh into table ls　时，生成的ls库中还是有.null.
不知何故？请行家指教！

[此贴子已经被作者于2016-5-26 09:45编辑过]

无人响应？

isnull函数

select isnull(a.*,0),isnull(b.*,0) from bmk a,cjk b where allt(a.xh)=allt(b.xh) into table ls　

select ISNULL(a.*,0),ISNULL(b.*,0) from 2015理科三批 as a FULL join 2014理科三批 as b on ALLTRIM(a.代码)=ALLTRIM(b.代码)
我试了提示：参数太多

[此贴子已经被作者于2016-5-26 10:21编辑过]

**VFP写法：
**用IIF()
select iif(isnull(字段1),0,字段1) as 字段1，iif(isnull(字段2),0,字段2) as 字段2,,,, from 表 into table 新表

如果你是字段是字符的，就改为 iif(isnull(字段3),'',字段3) as 字段3

[此贴子已经被作者于2016-5-26 10:44编辑过]

select iif(isnull(a.*),0,a.*),iif(isnull(b.*),0,b.*) from bmk a,cjk b where allt(a.xh)=allt(b.xh) into table ls

试了结果出现提示：[attach]84775[/attach]

[attach]84776[/attach]

[此贴子已经被作者于2016-5-26 16:39编辑过]

传个数据表，帮你看看

1).
SET null OFF
SET NULLDISPLAY TO " "
select a.*,b.* from 2015理科三批 as a FULL join 2014理科三批 as b on a.代码=b.代码
此时完全連接时没有null,只是空格
2).
SET null OFF
SET NULLDISPLAY TO " "
select a.*,b.* from 2015理科三批 as a FULL join 2014理科三批 as b on a.代码=b.代码 into table ls　

use ls
brow
就出现了unll

当退出fox后再进入时ls表出现了null

[此贴子已经被作者于2016-5-26 17:06编辑过]