sql插入空值null问题

Question

If instr(Request.Form("l_content"),"<img") > 0 or instr(Request.Form("l_content"),"<IMG") > 0 Then
list_pic_yn="1"
else
list_pic_yn=null
end if
解释：list_pic_yn是判断内容中是否有图片
然后再插入数据(部分字段省略)sqltest="Insert into dbo.list_h(list_title,list_pic_yn)values('"&list_title&"','"&list_pic_yn&"')"当用户提交的内容中没有图片时list_pic_yn=null 但是，它总是不能写入null值，sql此处的写入值为空
改为
sqltest="Insert into dbo.list_h(list_title,list_pic_yn,)values('"&list_title&"',"&list_pic_yn&")"
又不能正常的入库了

Answer 1

If instr(Request.Form("l_content")," <img") > 0 or instr(Request.Form("l_content")," <IMG") > 0 Then
list_pic_yn="1"
else
list_pic_yn is NULL
end if 

Answer 2

If instr(Request.Form("l_content")," <img") > 0 or instr(Request.Form("l_content")," <IMG") > 0 Then 
list_pic_yn="1" 
else 
list_pic_yn="null" 
end if sqltest="Insert into dbo.list_h(list_title,list_pic_yn,)values('"&list_title&"',"&list_pic_yn&")" 

Answer 3

sqltest="Insert into dbo.list_h(list_title,list_pic_yn)values('"&list_title&"',NULLIF('"&list_pic_yn&"',NULL))" 

Answer 4

If instr(Request.Form("l_content")," <img") > 0 or instr(Request.Form("l_content")," <IMG") > 0 Then
list_pic_yn="1"
else
list_pic_yn is null
end if 

Answer 5

你要把null也当字串 "null" 传进sqltest，才行哦，不然当然不能录入了

Answer 6

上面手误
sqltest="Insert into dbo.list_h(list_title,list_pic_yn)values('"&list_title&"',NULLIF('"&list_pic_yn&"',''))" 

Answer 7

Microsoft VBScript 编译器错误 错误 '800a03ea'语法错误/inc/add_cmd.asp，行 17list_pic_yn is NULL
------------^

Answer 8

jinjazz 
sqltest="Insert into dbo.list_h(list_title,list_pic_yn)values('"&list_title&"',NULLIF('"&list_pic_yn&"',''))" 
正确！

Answer 9

sqltest="Insert into dbo.list_h(list_title,list_pic_yn,)values('"&list_title&"',case when len('"&list_pic_yn&"')=0 then null else '"&list_pic_yn&"' end ) " 

Answer 10

If instr(Request.Form("l_content")," <img") > 0 or instr(Request.Form("l_content")," <IMG") > 0 Then 
list_pic_yn="1" 
else 
list_pic_yn=null 
end if If instr(Request.Form("l_content")," <img") > 0 or instr(Request.Form("l_content")," <IMG") > 0 Then 
list_pic_yn="1" 
else 
list_pic_yn is null 

Answer 11

sqltest="Insert into dbo.list_h(list_title,list_pic_yn,)values(isnull('"&list_title&"',''),isnull("&list_pic_yn&",''))"