主题：SQL数据库，代码中如何转换类型？

Dim txts As String = "要查找的字符数值日期"

txts = "'%" & txts & "%'"   '字符型

Dim dt As DataTable = DataTables("某表")

Dim dcname As String = "[金额]"

Dim ss As String

If dt.SourceType = 1 Then

    ss = "IIF(" & dcname & " Is NULL,null,Cstr(" & dcname & ") Like " & txts & ")"

End If

If dt.SourceType = 2 Then

    ss = "convert(" & dcname & ",'System.String') Like " & txts

    '请问这句,如何写?  (注：现时这样会报错)

End If