Question

 Public Sub Button1_Click(ByVal sender As System.Object, ByVal e As    
   System.EventArgs) Handles Button1.Click
    MyConn = New OleDbConnection
    MyConn.ConnectionString = connString
    ds = New DataSet
    tables = ds.Tables
    If R2.Checked Then
        da = New OleDbDataAdapter("Select * from [maint] where   
 [centrale]='" & centralev.Text & "' ", MyConn) 'Change items to your 
  database name
    End If
    If R1.Checked Then
        da = New OleDbDataAdapter("Select * from [maint] where 
 datevisite='" & dateintervention.Value.ToShortDateString() & "'  ", 
 MyConn) 'Change items to your database name
    End If
    da.Fill(ds, "maint") 'Change items to your database name
    Dim view As New DataView(tables(0))
    source1.DataSource = view
    DGV.DataSource = view

End Sub
End Class

我使用2 buttonradio来选择搜索条件，我有日期搜索问题，条件表达式中的数据类型不匹配。

Answer 1

尝试改变

不正确

 da = New OleDbDataAdapter("Select * from [maint] where 
 datevisite='" & dateintervention.Value.ToShortDateString() & "'  ", 
 MyConn) 'Change items to your database name

正确

da = New OleDbDataAdapter("Select * from [maint] where 
 datevisite='" & dateintervention.Value.ToString("yyyy-MM-dd") & "'  ", 
 MyConn) 'Change items to your database name

Example for format

Answer 2

扩展Plutonix对您的问题的评论，您可以尝试：

Dim cmd = New OleDbCommand("Select * from [maint] where datevisite = ?")

Dim param = New OleDbParameter("@datevisite", OleDbType.Date)
param.Value = dateintervention.Value

cmd.Parameters.Add(param)

da = New OleDbDataAdapter (cmd, MyConn)

通过这种方式，ADO.NET将照顾您使用OleDb语法所需格式化的正确日期值替换查询文本中的问号。您完全避免了字符串连接错误，并且您不需要学习所有可用OleDb数据类型的任何格式规则。

此外它应该更安全。

条件表达式中的数据类型不匹配。

2 个答案: