Problem saving Data to database using SQL Server and VB.Net

First, since your function does not return a value, make it a Sub:

 Public Sub Save()

        Dim oRow As Data.DataRow
        Dim oDb As New clsDBAccess(mvarServer, mvarDatabase)
        Dim strSQL As String = "Select * from tblReports Where ReportID = " & mvarRecId
        Dim DB_CONN As String = oDb.GetConnectionString
        Dim objDA As New SqlClient.SqlDataAdapter(strSQL, DB_CONN)
        Dim oDS As New Data.DataSet

        objDA.Fill(oDS)
        oRow = oDS.Tables(0).Rows(0)
        If oRow Is Nothing Then oRow = oDS.Tables(0).NewRow

        PopulateRowFromObject(oRow)
        Try
            objDA.Update(oDS)
        Catch ex As Exception

        End Try



    End Sub

also what does PopulateRowFromObject do?

Error is :       "Update requires a valid UpdateCommand when passed DataRow collection with modified rows."      

PopulateRowFromObject  Populates the data row with data from this object...

Public Sub Save()

        Dim oRow As Data.DataRow
        Dim oDb As New clsDBAccess(mvarServer, mvarDatabase)
        Dim strSQL As String = "Select * from tblReports Where ReportID = " & mvarRecId
        Dim DB_CONN As String = oDb.GetConnectionString
objDA.SelectCommand=strSQL
        Dim objDA As New SqlClient.SqlDataAdapter(strSQL, DB_CONN)
        Dim oDS As New Data.DataSet

dim updateCmd as SqlCommand
                  
                  
                  ''Create update command for SqlDataAdapter
                  updateCmd = new SqlCommand("UPDATE tblReports SET field1=@value1, field2=@value2.... WHERE ....", objDA.SelectCommand.Connection)
                  
                  //Add parameters for update command
                  updateCmd.Parameters.Add(new SqlParameter("@value1", SqlDbType.VarChar))
                  updateCmd.Parameters("@value1") = .....


                  updateCmd.Parameters.Add(new SqlParameter("@value2", SqlDbType.VarChar))
                  updateCmd.Parameters("@value2")=...
            

                  ''Initialize the UpdateCommand of SqlDataAdapter
                  da.UpdateCommand = updateCmd


        objDA.Fill(oDS)
        oRow = oDS.Tables(0).Rows(0)
        If oRow Is Nothing Then oRow = oDS.Tables(0).NewRow

        PopulateRowFromObject(oRow)
        Try
            objDA.Update(oDS)
        Catch ex As Exception

        End Try

    End Sub

Not was i was going for....
I was missing " Dim cb As SqlClient.SqlCommandBuilder = New SqlClient.SqlCommandBuilder(objDA)"
Seems the right answer is....

    Public Function Save()

        Dim oRow As Data.DataRow
        Dim oDb As New clsDBAccess(mvarServer, mvarDatabase)
        Dim strSQL As String = "Select * from tblReports Where ReportID = " & mvarRecId
        Dim DB_CONN As String = oDb.GetConnectionString
        Dim objDA As New SqlClient.SqlDataAdapter(strSQL, DB_CONN)
        Dim cb As SqlClient.SqlCommandBuilder = New SqlClient.SqlCommandBuilder(objDA)

        Dim oDS As New Data.DataSet

        objDA.Fill(oDS)
        oRow = oDS.Tables(0).Rows(0)
        If oRow Is Nothing Then oRow = oDS.Tables(0).NewRow

        PopulateRowFromObject(oRow)

        Try
            objDA.Update(oDS)

        Catch ex As Exception
            Console.WriteLine(ex)
        End Try

    End Function

well, does it work?

also as I've said, change Function to Sub

Ya it works now....  I need it as a function as it will return a boolean success or fail flag...

then change it to

 Public Function Save() As Boolean
dim bResult as boolean
        Dim oRow As Data.DataRow
        Dim oDb As New clsDBAccess(mvarServer, mvarDatabase)
        Dim strSQL As String = "Select * from tblReports Where ReportID = " & mvarRecId
        Dim DB_CONN As String = oDb.GetConnectionString
        Dim objDA As New SqlClient.SqlDataAdapter(strSQL, DB_CONN)
        Dim cb As SqlClient.SqlCommandBuilder = New SqlClient.SqlCommandBuilder(objDA)

        Dim oDS As New Data.DataSet

        objDA.Fill(oDS)
        oRow = oDS.Tables(0).Rows(0)
        If oRow Is Nothing Then oRow = oDS.Tables(0).NewRow

        PopulateRowFromObject(oRow)

        Try
            objDA.Update(oDS)
    bResult=True
        Catch ex As Exception
            Console.WriteLine(ex)
         bResult=False
        End Try
    Save=bResult
    End Function

otherwise function will not return anything

While Im all for giving credit where credit is due...  YZlat didnt solve this problem At all...  He offered a solution that was not at all in the style required....

first of all, the function should return a value and yours did not return anything, so either you should change it to Sub or return a boolean value from it

Dude that is not an issue even worth thinking about :)

Here, I think you will benifit from this article:

http://getdotnetco.web101.discountasp.net/GdncStore/free/Articles/Sub%20Statement%20vs%20Function%20Statement.htm