我有以下错误但我不确定为什么我收到此错误。当我尝试向数据库添加数据时，我收到此错误。
条件表达式中的数据类型不匹配。
我正在处理的代码如下。有人可以帮忙吗？谢谢
Private Sub RefreshData()
If Not cnn.State = ConnectionState.Open Then
'open connection
cnn.Open()
End If
Dim da As New OleDb.OleDbDataAdapter("SELECT Item ID as [Item ID], " & _
"Item Name as [Item Name], " & _
"Item Type as [Item Type], " & _
"Quantity as [Quantity], " & _
"Min Shelf Stock as [Min Shelf Stock], " & _
"Purchase Price as [Purchase Price], Note " & _
" From Product ORDER BY Item ID", cnn)
Dim dt As New DataTable
'fill data to datatable
da.Fill(dt)
'offer data in data table into datagridview
Me.dgvData.DataSource = dt
'Close the connection
cnn.Close()
End Sub
Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
Dim cmd As New OleDb.OleDbCommand
If Not cnn.State = ConnectionState.Open Then
'The line of code below opens the connection to the database if it isnt open
cnn.Open()
End If
cmd.Connection = cnn
'Check whether to add new or update
If Me.txtItemID.Tag & "" = "" Then
'Add new
'The line of coding below adds data to table
cmd.CommandText = "INSERT INTO Product ([Item Id], [Item Name], [Item Type], [Quantity], [Min Shelf Stock], [Purchase Price], [Note]) VALUES (@id, @name, @iType, @quantity, @minshelfstock, @price, @note)"
cmd.Parameters.AddWithValue("@id", txtItemID.Text)
cmd.Parameters.AddWithValue("@name", txtItemName.Text)
cmd.Parameters.AddWithValue("@iType", cboItemType.Text)
cmd.Parameters.AddWithValue("@quantity", txtQuantity.Text)
cmd.Parameters.AddWithValue("@minshelfstock", txtMinShelfStock.Text)
cmd.Parameters.AddWithValue("@price", txtPurchasePrice.Text)
cmd.Parameters.AddWithValue("@note", txtNote.Text)
cmd.ExecuteNonQuery()
Else
'Update data in the table
cmd.CommandText = "UPDATE Product " & _
" SET [Item ID]=" & Me.txtItemID.Text & _
", [Item Name]='" & Me.txtItemName.Text & "'" & _
", [Item Type]='" & Me.cboItemType.Text & "'" & _
", [Quantity]=" & Me.txtQuantity.Text & "" & _
", [Min Shelf Stock]=" & Me.txtMinShelfStock.Text & "" & _
", [Purchase Price]=" & Me.txtPurchasePrice.Text & "" & _
", [Note]='" & Me.txtNote.Text & "'" & _
" WHERE [Item ID]=" & Me.txtItemID.Tag
cmd.ExecuteNonQuery()
End If
'Refresh data in list
RefreshData()
'Clear the form
Me.btnClear.PerformClick()
'The code below closes the connection to the database
cnn.Close()
End Sub
Private Sub Product_Load(sender As Object, e As EventArgs) Handles Me.Load
cnn = New OleDb.OleDbConnection
cnn.ConnectionString = "Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\inventorysystem.mdb"
'
'Get the data into a list
Me.RefreshData()
End Sub
Private Sub btnEdit_Click(sender As Object, e As EventArgs) Handles btnEdit.Click
'check for the selected item in list
If Me.dgvData.Rows.Count > 0 Then
If Me.dgvData.SelectedRows.Count > 0 Then
Dim intItemID As Integer = Me.dgvData.SelectedRows(0).Cells("Item ID").Value
'Get the data from database followed Item ID
'Open the connection
If Not cnn.State = ConnectionState.Open Then
cnn.Open()
End If
'Get the data into the datatable
Dim da As New OleDb.OleDbDataAdapter("SELECT * FROM Product " & _
" WHERE Item ID=" & intItemID, cnn)
Dim dt As New DataTable
da.Fill(dt)
Me.txtItemID.Text = intItemID
Me.txtItemName.Text = dt.Rows(0).Item("Item Name")
Me.cboItemType.Text = dt.Rows(0).Item("Item Type")
Me.txtQuantity.Text = dt.Rows(0).Item("Quantity")
Me.txtMinShelfStock.Text = dt.Rows(0).Item("Min Shelf Stock")
Me.txtPurchasePrice.Text = dt.Rows(0).Item("Purchase Price")
Me.txtNote.Text = dt.Rows(0).Item("Note")
'
'Hide the ID to be edited in TAG od txtItemID in case ID is changed
Me.txtItemID.Tag = intItemID
'Change the add button to update
Me.btnAdd.Text = "Update"
'Disable the Edit button
Me.btnEdit.Enabled = False
'Close the connection
cnn.Close()
End If
End If
End Sub
Private Sub btnDelete_Click(sender As Object, e As EventArgs) Handles btnDelete.Click
'Check for the selected item in the list
If Me.dgvData.Rows.Count > 0 Then
If Me.dgvData.SelectedRows.Count > 0 Then
Dim intItemID As Integer = Me.dgvData.SelectedRows(0).Cells("Item ID").Value
'Open the connection
If Not cnn.State = ConnectionState.Open Then
cnn.Open()
End If
'Delete data
Dim cmd As New OleDb.OleDbCommand
cmd.Connection = cnn
cmd.CommandText = "DELETE FROM Product WHERE Item ID" & intItemID
cmd.ExecuteNonQuery()
'Refresh the data
Me.RefreshData()
'Close the connection
cnn.Close()
End If
End If
End Sub
结束班
答案 0 :(得分：1)
问题是AddWithValue方法。此方法创建参数及其数据类型。但是，为了这样做，它会查看作为第二个参数传递的值的数据类型。如果此值是一个字符串（就像您总是传递文本框的Text属性一样），那么它会构建一个类型为OleDbType.LongVarWChar或类似的参数。当然，这不是您的数据库对您要更新的一个或多个字段的期望。
您需要检查字段的数据类型并传递类似数据类型的参数，并将转换应用于文本框的字符串值。
例如，如果price字段的类型为numeric decimal，则需要编写
cmd.Parameters.AddWithValue("@price", Convert.ToDecimal(txtPurchasePrice.Text))
答案 1 :(得分：0)
可能是由于数据数据类型。
尝试this
cmd.Parameters.Add("@id", SqlDbType.Int).Value = txtItemId.Text;
cmd.Parameters.Add("@name", SqlDbType.VarChar, 20).Value = txtItemName.Text;
cmd.Parameters.Add("@iType", SqlDbType.VarChar, 20).Value = cboItemType.Text;
cmd.Parameters.Add("@quantity", SqlDbType.Int).Value = txtQuantity.Text;
cmd.Parameters.Add("@minshelfstock", SqlDbType.Int).Value = txtMinShelfStock.Text;
cmd.Parameters.Add("@price", SqlDbType.Int).Value = txtPurchasePrice.Text;
cmd.Parameters.Add("@note", SqlDbType.VarChar, 20).Value = txtNote.Text;
不确定它是否是您想要实现的目标。