运行此代码时，我似乎得到了一个未处理的 OleDb 异常，我真的不明白为什么......
附上代码 谢谢！詹姆士
Module DataAccess
Private Builder As New OleDb.OleDbConnectionStringBuilder With
{
.Provider = "Microsoft.ACE.OLEDB.12.0",
.DataSource = IO.Path.Combine(Application.StartupPath, "Database1.accdb")
}
''' <summary>
''' Used to remove the current item selected in the txtFirstName text box.
''' </summary>
''' <param name="Name"></param>
''' <remarks></remarks>
Public Sub RemmoveFemale(ByVal Name As String)
Using cn As New OleDb.OleDbConnection With
{
.ConnectionString = Builder.ConnectionString
}
Using cmd As New OleDb.OleDbCommand With {.Connection = cn}
cmd.CommandText =
<SQL>
DELETE FROMCustomerNames WHERE CustomerName = @CustomerName
</SQL>.Value
cmd.Parameters.Add(New OleDb.OleDbParameter With {.DbType = DbType.String, .ParameterName = "@CustomerName", .Value = Name})
cn.Open()
Dim Affected As Int32 = cmd.ExecuteNonQuery
End Using
End Using
End Sub
''' <summary>
''' Called in Form1 on FormClosing event to update the database table if
''' needed.
''' </summary>
''' <param name="sender"></param>
''' <remarks></remarks>
Public Sub UpdateFemaleNames(ByVal sender As AutoCompleteStringCollection)
Dim NewNames As New List(Of String)
Using cn As New OleDb.OleDbConnection With
{
.ConnectionString = Builder.ConnectionString
}
Using cmd As New OleDb.OleDbCommand With {.Connection = cn}
cmd.CommandText =
<SQL>
SELECT CustomerName
FROM CustomerNames
WHERE CustomerName = @CustomerName
</SQL>.Value
cmd.Parameters.Add(New OleDb.OleDbParameter With {.DbType = DbType.String, .ParameterName = "@CustomerName"})
cn.Open()
For x As Int32 = 0 To sender.Count - 1
cmd.Parameters("@CustomerName").Value = sender.Item(x)
Dim Result As String = CStr(cmd.ExecuteScalar)
If String.IsNullOrWhiteSpace(Result) Then
NewNames.Add(sender.Item(x))
End If
Next
If NewNames.Count > 0 Then
cmd.CommandText =
<SQL>
INSERT INTO CustomerNames (CustomerName,Gender) VALUES (@CustomerNamee,@Gender)
</SQL>.Value
cmd.Parameters.Add(New OleDb.OleDbParameter With {.DbType = DbType.String, .ParameterName = "@Gender", .Value = "Female"})
For Each Item In NewNames
cmd.Parameters("@CustomerName").Value = Item
cmd.ExecuteReader()
Next
End If
End Using
End Using
End Sub
''' <summary>
''' Used in Form1 DataGridView1 for learning purposes only
''' </summary>
''' <returns></returns>
''' <remarks></remarks>
Public Function AllFemaleNames() As DataTable
Dim dt As New DataTable
Using cn As New OleDb.OleDbConnection With
{
.ConnectionString = Builder.ConnectionString
}
Using cmd As New OleDb.OleDbCommand With {.Connection = cn}
cmd.CommandText =
<SQL>
SELECT Identifier, CustomerName
FROM CustomerNames
WHERE Gender = 'Female'
ORDER BY CustomerName;
</SQL>.Value
cn.Open()
dt.Load(cmd.ExecuteReader)
End Using
End Using
Return dt
End Function
''' <summary>
''' Load only female first names into the auto complete source
''' </summary>
''' <returns></returns>
''' <remarks></remarks>
Public Function LoadFemaleNames() As AutoCompleteStringCollection
Dim TheNameList As New AutoCompleteStringCollection
Using cn As New OleDb.OleDbConnection With
{
.ConnectionString = Builder.ConnectionString
}
Using cmd As New OleDb.OleDbCommand With {.Connection = cn}
cmd.CommandText =
<SQL>
SELECT CustomerName
FROM CustomerNames
WHERE Gender = 'Female'
ORDER BY CustomerName;
</SQL>.Value
cn.Open()
Dim Reader As OleDb.OleDbDataReader = cmd.ExecuteReader
If Reader.HasRows Then
While Reader.Read
TheNameList.Add(Reader.GetString(0))
End While
Reader.Close()
End If
End Using
End Using
Return TheNameList
End Function
End Module
Module StringExtensions
<Runtime.CompilerServices.Extension()> _
Public Function ProperCase(ByVal sender As String) As String
Dim TI As System.Globalization.TextInfo = New System.Globalization.CultureInfo("en-US", False).TextInfo
Return TI.ToTitleCase(sender.ToLower)
End Function
End Module
''' <summary>
''' Simple demo for auto complete adding items that are not in the list when pressing ENTER in TextBox1.
''' </summary>
''' <remarks></remarks>
Public Class Form1
Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
UpdateFemaleNames(txtFirstName.AutoCompleteCustomSource)
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
txtFirstName.AutoCompleteMode = AutoCompleteMode.SuggestAppend
txtFirstName.AutoCompleteSource = AutoCompleteSource.CustomSource
txtFirstName.AutoCompleteCustomSource = LoadFemaleNames()
' The next two lines are for demo purposes only to see what is in the list for the TextBox with First names
DataGridView1.DataSource = AllFemaleNames()
DataGridView1.Columns("CustomerName").AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill
End Sub
Private Sub TextBox1_KeyDown(sender As Object, e As KeyEventArgs) Handles txtFirstName.KeyDown
If e.KeyCode = Keys.Enter Then
If Not String.IsNullOrWhiteSpace(txtFirstName.Text) Then
If Not txtFirstName.AutoCompleteCustomSource.Contains(txtFirstName.Text.ToLower) Then
txtFirstName.AutoCompleteCustomSource.Add(txtFirstName.Text.ProperCase)
End If
txtFirstName.Text = txtFirstName.Text.ProperCase
e.SuppressKeyPress = True
End If
End If
End Sub
Private Sub cmdRemoveName_Click(sender As Object, e As EventArgs) Handles cmdRemoveName.Click
If Not String.IsNullOrWhiteSpace(txtFirstName.Text) Then
Dim CurrentName As String = txtFirstName.Text.Trim.ProperCase
If My.Dialogs.Question(String.Format("Remove '{0}'", CurrentName)) Then
RemmoveFemale(CurrentName)
txtFirstName.AutoCompleteCustomSource.Remove(txtFirstName.Text)
txtFirstName.Text = ""
End If
End If
End Sub
End Class