Warning message when adding data to database

[Jagavi]

Here I got my connection to my database with this code

    Public Sub connection()
        connection.ConnectionString = "Data Source=localhost;Initial Catalog=base;Integrated Security=true"
        connection.Open()
        If connection.State = ConnectionState.Open Then
            MsgBox("Connection was successful", MsgBoxStyle.Exclamation, "Status")
        Else
            MsgBox("Connection failed", MsgBoxStyle.Critical, "Status")
        End If
        connection.Close()

Now I try to add data in my database, data taken from the TextBox, but I get this warning when I click "save"

A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in system.data.dll

Here is my code

Try
            connection()
            Dim strRequest As String = "SELECT * FROM Coaches"
            Dim dtt As DataTable
            Dim oSqlDataAdapter As New SqlDataAdapter(strRequest, connection)
            Dim oDataSet As New DataSet("Coaches")
            oSqlDataAdapter.Fill(oDataSet, "Coaches")
            dtt = oDataSet.Tables("Coaches")
 
            oSqlDataAdapter.InsertCommand = New SqlCommand("INSERT INTO Coaches(Name,Surname,Address,Telephone) Values(@TextBoxName_E,@TextBoxSurname_E,@TextBoxAd_E,@TextBoxTel_E)", connection)
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxName_E", SqlDbType.Int, 30, "TextBoxName_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxSurname_E", SqlDbType.NChar, 15, "TextBoxSurname_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxAd_E", SqlDbType.Int, 100, "TextBoxAd_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxTel_E", SqlDbType.Int, 100, "TextBoxTel_E")
 
            Dim oDataRow As DataRow
            Dim byteArray As Byte() = {}
 
            oDataRow = oDataSet.Tables("Coaches").NewRow
            oDataRow("TextBoxName_E") = TextBoxName_E.Text
            oDataRow("TextBoxSurname_E") = TextBoxSurname_E.Text
            oDataRow("TextBoxAd_E") = TextBoxAd_E.Text
            oDataRow("TextBoxTel_E") = TextBoxTel_E.Text
 
            oDataSet.Tables("Coaches").Rows.Add(oDataRow)
            oSqlDataAdapter.Update(oDataSet, "Coaches")
 
            oDataSet.Clear()
            oSqlDataAdapter.Fill(oDataSet, "Coaches")
            dtt = oDataSet.Tables("Coaches")
            MsgBox("Article successfully registered with", MsgBoxStyle.Information, "Status")
            connection.Close()
        Catch
            MsgBox("Failed registration")
        End Try

[void]

Your Sub Connection closes the connection immediately after opening, so it will not work.

On the other hand, if the Open method is successful, the connection status will inevitably open. And so the Open method fails, you have an exception, so anyway you will never pass in the else.

You should not use the same connection object each time it does that bring you problems. Instead use a local variable that you initialized with the result of a function GetConnection:

    Public Function GetConnection() As SqlConnection
        Dim connection As New SqlConnection()
        connection.ConnectionString = "Data Source=localhost;Initial Catalog=base;Integrated Security=true"
        connection.Open()
        Return connection
    End Function
 
...

Try
        Using (connection As GetConnection())
            Dim strRequest As String = "SELECT * FROM Coaches"
            Dim dtt As DataTable
            Dim oSqlDataAdapter As New SqlDataAdapter(strRequest, connection)
            Dim oDataSet As New DataSet("Coaches")
            oSqlDataAdapter.Fill(oDataSet, "Coaches")
            dtt = oDataSet.Tables("Coaches")
 
            oSqlDataAdapter.InsertCommand = New SqlCommand("INSERT INTO Coaches(Name,Surname,Address,Telephone) Values(@TextBoxName_E,@TextBoxSurname_E,@TextBoxAd_E,@TextBoxTel_E)", connection)
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxName_E", SqlDbType.Int, 30, "TextBoxName_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxSurname_E", SqlDbType.NChar, 15, "TextBoxSurname_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxAd_E", SqlDbType.Int, 100, "TextBoxAd_E")
            oSqlDataAdapter.InsertCommand.Parameters.Add("@TextBoxTel_E", SqlDbType.Int, 100, "TextBoxTel_E")
 
            Dim oDataRow As DataRow
            Dim byteArray As Byte() = {}
 
            oDataRow = oDataSet.Tables("Coaches").NewRow
            oDataRow("TextBoxName_E") = TextBoxName_E.Text
            oDataRow("TextBoxSurname_E") = TextBoxSurname_E.Text
            oDataRow("TextBoxAd_E") = TextBoxAd_E.Text
            oDataRow("TextBoxTel_E") = TextBoxTel_E.Text
 
            oDataSet.Tables("Coaches").Rows.Add(oDataRow)
            oSqlDataAdapter.Update(oDataSet, "Coaches")
 
            oDataSet.Clear()
            oSqlDataAdapter.Fill(oDataSet, "Coaches")
            dtt = oDataSet.Tables("Coaches")
            MsgBox("Article successfully registered with", MsgBoxStyle.Information, "Status")
 
        End Using ' The connection is automatically closed here
 
        Catch ex As Exception
            MsgBox("Failed registration : " & ex.ToString())
        End Try

[Jagavi]

I found an error in this line of code

Using (connection As GetConnection())

')' Expected .... I can not find where

[void]

Ah yes sorry ... I am not very use to write VB codes

Using (connection As SqlConnection = GetConnection())

[Jagavi]

Sorry but I am still getting the same error, missing ')' from VB

Using (connection As SqlConnection = GetConnection())

[void]

I am really struggling with the VB syntax... I think you should try "Using" without parentheses:

Using connection As SqlConnection = GetConnection()