ADD SQL QUERY STAT

问题

I'm trying to update the records from textboxes into the Access database, I'm wondering every time I hit save, it generates an error

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll

Additional information: No value given for one or more required parameters.

Highlighting .ExecuteNonQuery()

What does it mean? It's preventing me to run my code :(

Private Sub SaveButton_Click(sender As Object, e As EventArgs) Handles SaveButton.Click
        Dim empNum As String
        Dim empFname As String
        Dim empLname As String
        Dim empDept As String
        Dim empStat As String
        Dim empYears As String



        empNum = eNumText.Text
        empFname = empFnameText.Text
        empLname = empLnameText.Text
        empDept = DeptText.Text
        empStat = StatText.Text
        empYears = yearstext.Text

        con.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source= c:\Databse\Company_db.accdb"
        con.Open()


        Dim SqlAdapter As New OleDbDataAdapter
        Dim Table As New DataTable

        Dim sqlQuery As String = "UPDATE tbl_empinfo " & _
        "SET FirstName=empFname, LastName=empLname, Department=empDept, " & _
        "Status=empStat, Years=empYears " & _
        "WHERE empID=empNum"

        Dim cmd As New OleDbCommand
        With cmd
            .CommandText = sqlQuery
            .Connection = con
            .Parameters.AddWithValue("FirstName", empFname)
            .Parameters.AddWithValue("LastName", empLname)
            .Parameters.AddWithValue("Department", empDept)
            .Parameters.AddWithValue("Status", empStat)
            .Parameters.AddWithValue("Years", empYears)
            .ExecuteNonQuery()
        End With

        Using cmd2 = New OleDbCommand(sqlQuery, con)
            cmd.Parameters.AddWithValue("FirstName", empFname)
            cmd.Parameters.AddWithValue("LastName", empLname)
            cmd.Parameters.AddWithValue("Department", empDept)
            cmd.Parameters.AddWithValue("Status", empStat)
            cmd.Parameters.AddWithValue("Years", empYears)
            cmd.ExecuteNonQuery()
        End Using

        sqlQuery = "SELECT * FROM tbl_empinfo "
        Dim cmd1 As New OleDbCommand
        Dim da As New OleDbDataAdapter


        With cmd1
            .CommandText = sqlQuery
            .Connection = con
            With SqlAdapter
                .SelectCommand = cmd1
                .Fill(Table)
            End With
            With DataGridView1
                .DataSource = Table
            End With
        End With

        con.Close()
    End Sub

回答1:

You are trying to set an UPDATE command text for the SelectCommand of the Adapter. This, of course has no way to be successful. Last but not least the UPDATE command text doesn't contain a WHERE clause, and so, if executed, it updates every record in the table tbl_empinfo with the same data.

In this context there is no need to use an adapter. You could simply execute the command, providing an appropriate WHERE clause and the values for the other parameters

   Dim sqlQuery As String = "UPDATE tbl_empinfo " & _
        "SET FirstName=?, LastName=?, Department=?, " & _
        "Status=?, Years=? " & _
        "WHERE empID=?"

    Dim cmd As New OleDbCommand
    With cmd
        .CommandText = sqlQuery
        .Connection = con
        .Parameters.AddWithValue("@p1", empFName)
        .Parameters.AddWithValue("@p2", empLName)
        .Parameters.AddWithValue("@p3", empDept)
        .Parameters.AddWithValue("@p4", empStat)
        .Parameters.AddWithValue("@p5", empYears)
        .Parameters.AddWithValue("@p6", empNum)
        .ExecuteNonQuery()
    End With

After this you could call the code that reloads the data to fill your grid

    sqlQuery = "SELECT * FROM tbl_empinfo"
    Dim cmd1 As New OleDbCommand
    Dim da As New OleDbDataAdapter
    Dim Table As New DataTable

    With cmd1
        .CommandText = sqlQuery
        .Connection = con
        With da
            .SelectCommand = cmd1
            .Fill(Table)
        End With
        With DataGridView1
            .DataSource = Table
        End With
    End With

Notice that I have changed the name of the command and the adapter to a less confusing names. SqlCommand And SqlDataAdapter are the names of the classes equivalent to the OleDbCommand and OleDbDataAdapter but used for Sql Server. At first sight I was thinking that you were trying to use the SqlClient classes to update an MS-Access database.

来源：https://stackoverflow.com/questions/23185478/add-sql-query-stat