一段关于ACCESS查询的VB.NET代码疑惑
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.ClickDim mcnstr As String = "Provider=Microsoft.ACE.OLEDB.12.0;DATA SOURCE=F:\11.accdb"
Dim mcn As New OleDbConnection(mcnstr)
mcn.Open()
Dim sql As String = "select * from (select [姓名] from [表1] where [年龄]='21') as a where [成绩]='99'"
Dim cmd As OleDbCommand = New OleDbCommand(sql, mcn)
Dim mread As OleDbDataReader = cmd.ExecuteReader()
While mread.Read
TextBox1.Text = mread(1)
End While
mcn.Close()
End Sub
上面这段代码运行到“Dim mread As OleDbDataReader = cmd.ExecuteReader()”时出错,错误为“至少一个参数未被指定”
求高手帮助啊,不胜感激~~~~~~~ --------------------编程问答-------------------- 换一下
select [姓名] from (select * from [表1] where [年龄]='21') as a where [成绩]='99' --------------------编程问答-------------------- Dim sql As String = "select * from (select [姓名] from [表1] where [年龄]='21') as a where [成绩]='99'"
這句話錯誤!
改為:
Dim sql As String = "select * from (select [姓名] from [表1] where [年龄]='21') as a where a.[成绩]='99'"
或者:
Dim sql As String = "select [姓名] from [表1] where [年龄]='21' and [成绩]='99'"
注:本來就簡單的查詢語句,為什麽要複雜化?盡可能少用嵌套子查詢。
补充:.NET技术 , VB.NET