vb.net---SQL数据类型转换(在线)

[firstlight29]

vb.net:
strQuery += "AND a.fVehValoD < = '" & txtnum.text & "'"
要求：fVehValoD(float) <=txtnum.text(某一数值)
问： txtnum.text 该如何转换？

已尝试：dim a as double=cDbl(txtnum.text)
SqlDataAdapter.Fill(DsDataSet, "SearchResult") 此句报错

[firstlight29]

Dim a As Double = CDbl(CmbValRange.Text)

strQuery = "SELECT a.fVehValoD, b.fVehFuelConsume, b.vVehName, b.vVehType, b.vVehMaker, b.cVehTransmissionType FROM VehRentVal a, VehicleInfo b WHERE a.vVehName in (SELECT DISTINCT(vVehName) FROM VehRentInfo WHERE iVehIsRent=0 AND iVehIsOk=1) AND a.vVehName = b.vVehName"

If Not BSearchStrEmpty Then
strQuery += "AND a.fVehValoD < = a"
End If

DsDataSet = New DataSet()
SqlDataAdapter.SelectCommand = SqlSelectCommand
SqlDataAdapter.SelectCommand.CommandText = strQuery
SqlDataAdapter.SelectCommand.Connection = cn
SqlDataAdapter.Fill(DsDataSet, "SearchResult")

SqlDataAdapter.Fill(DsDataSet, "SearchResult") <－报错 系统错误

[CMIC]

strQuery += " AND a.fVehValoD < =" & a'注意AND前要有空格。

[dzq_1]

改成：
strQuery += "AND a.fVehValoD < =a

[meetweb]

在保证txtnum.text是数字的前提下
Dim a As Double
a = CType(Me.txtnum.text, Double)
MessageBox.Show(a)
该转换是正确的,我怀疑你的错误在于定义DataSet其中字段非doule类型

[firstlight29]

再问：
DataSet该如何设置？
谢谢！

[kexian]

把'去掉就可以了
strQuery += "AND a.fVehValoD < = " & txtnum.text

[cnhgj]

不用设置啊
把datagrid绑定就好了