[求助]请问空值如何跟字符串连接 - 专家坐堂 - Foxtable(狐表) - 新一代数据库软件，完美融合Access、Foxpro、Excel、vb.net之优势，人人都能掌握的快速软件开发工具!

事情如下

我通过做了两个 iff （条件，空值，结果是：）；

最终我想把两辆 iff 的结果连接成字符串，发现，当条件成立是，为空值的时候，无法正常的连接成字符串

想问一下，如果将空值跟正常的字符串连接起来

Dim t1 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("text1")

Dim t2 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("text2")

Dim t3 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("text3")

Dim r1 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("jytxt")

Dim r2 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("sytxt")

Dim r3 As RibbonMenu.TextBox = RibbonTabs("detail").Groups("汇总").Items("cost")

Dim t1_txt As String = IIF(t1.Text.Length = 0 ,''," 类别: "& t1.text &" " )

Dim t2_txt As String = IIF(t1.Text.Length = 0 ,''," 名称: "& t2.text &" " )

Dim t3_txt As String = IIF(t1.Text.Length = 0 ,''," 规格型号: "& t3.text &" " )

Dim j As String = t1_txt & t2_txt & t3_txt

Dim r1_txt As String = r1.Text

Dim r2_txt As String = r2.Text

Dim r3_txt As String = r3.Text

Tables("查询表").AddNew

Dim r As Row = Tables("查询表").Current

r("内容") = j

r("净用量") = r1_txt

r("实用量") = r2_txt

r("不含税合计") = r3_txt

改成单引号后报错