Issues adding column from DGV to SQL server - sql-server

Question

I'm sorry if the title is a little vague but I wasn't sure how to put it in a short space.
For context, I have a save button, which is when changes made are updated in the SQL server database. This works fine when adding rows, or changing values, even deleting rows. Nothing wrong there.
However, when I try to add or remove columns the app becomes a bit more problematic and simply does not update added/removed columns in the database and doesnt throw an error.
The only way I can get adding or removing columns to work is to use a sql query on the add/delete buttons, but this saves directly to the server - which i do not want.
What I need is for the changes to appear in the table, and then only update the database when the save button is clicked.
My code is here --- (Note, this is done over three forms, I have the main form with the table, plus two more that are used for inputting the name of the "trainer column" that is to be added or removed)
Private Function save() ''''' Main form
Try
ds.Tables(0).AcceptChanges()
da.Update(ds)
DataTableColours()
MessageBox.Show("Data updated successfully.")
Catch
MessageBox.Show("Data failed to update properly. Please ensure you are connected to the Baltic network and try again. If the problem persists, seek IT support.")
End Try
End Function
Public Function AddTrainerFunc() ''''' Main form
'Dim SqlAddCol As String = "ALTER TABLE MasterTrainerSchedule ADD [" & TrainerName.Trim() & "] nvarchar(255)"
'Using con As New OleDbConnection(cs)
' Using cmd As New OleDbCommand(SqlAddCol, con)
' con.Open()
' cmd.ExecuteNonQuery()
' End Using
'End Using
ds.Tables(0).Columns.Add(TrainerName.Trim()).DefaultValue = " "
RefreshBtn()
End Function
Public Function delTrainerFunc() ''''' Main form
Dim SqlDelCol As String = "ALTER TABLE MasterTrainerSchedule DROP COLUMN [" & TrainerName.Trim() & "]"
Using con As New OleDbConnection(cs)
Using cmd As New OleDbCommand(SqlDelCol, con)
con.Open()
cmd.ExecuteNonQuery()
End Using
End Using
ds.Tables(0).Columns.Remove(TrainerName)
DelTrainer.Close()
RefreshBtn()
MessageBox.Show("Trainer '" & TrainerName.Trim() & "' has been deleted from the table.")
End Function
Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click '''''Add Column Form
If Not txtTrainerName.Text = "Trainer Name Here" Or txtTrainerName.Text = "" Then
MTS.TrainerName = txtTrainerName.Text
MTS.Enabled = True
Me.Close()
MTS.AddTrainerFunc()
Else
MessageBox.Show("Please input a name for the trainer in the text box above.")
End If
End Sub
Private Sub btnDel_Click(sender As Object, e As EventArgs) Handles btnDel.Click ''''' Delete Column form
Dim delYN As Integer = MessageBox.Show("Are you sure you want to delete '" & cmbTrainers.Text & "' from the MTS table? The action will be permanent!", "Delete Trainer?", MessageBoxButtons.YesNo)
If delYN = DialogResult.Yes Then
MTS.Enabled = True
MTS.delTrainerFunc()
End If
End Sub
Sorry if this was a bit long winded but... I can't seem to find a way to add columns to the Database quite how I wanted too, neither through googling the answer, nor through simple experimentation, so I came here in the hopes that one of you may be able to help. Thanks in advance for any help you can provide.
EDIT --- I am using oleDB as the connection to sql, if this helps.
EDIT 2 --- Here's a few screenshots in case you wish to have a look at the visual side of the app.
The add form being used. (with the main form in the background. Sorry I couldnt get that on its own - only allowed two links with 6 rep!)
And the delete trainer form. The dropdown lists everyone in the table for you, then prompts you when you click "delete"
EDIT 3 --- Okay, I know the normalizing tables thing that Sean was on about could have worked, but it might have required quite a big change to the server used and to the program as well. I managed to find a simpler way to get this working that calls the sql queries to add or remove columns to the table on the save, only after the changes have been made to the data grid.
Heres some code in case anyone was interested. It's a little messy and can probably be optimized a bit, but this works for me regardless.
` Private Function save()
Try
da.Update(ds)
DataTableColours()
MessageBox.Show("Data updated successfully.")
Catch
MessageBox.Show("Data failed to update properly. Please ensure you are connected to the Baltic network and try again. If the problem persists, seek IT support.")
End Try
'This section reads the SQL server for column names, and adds any that are listed in the DGV, but not the database. I know its a little messy but itll do.
Dim columnnum As Integer = -1
Dim columname As String
For Each column In ds.Tables(0).Columns
columnnum = columnnum + 1
columname = dgvSchedule.Columns(columnnum).HeaderText
If Not ds2.Tables(0).Columns.Contains(columname) Then
MessageBox.Show("Table does not include " & columname)
Dim SqlAddCol As String = "ALTER TABLE MasterTrainerSchedule ADD [" & columname.Trim() & "] nvarchar(255)"
Using con As New OleDbConnection(cs)
Using cmd As New OleDbCommand(SqlAddCol, con)
con.Open()
cmd.ExecuteNonQuery()
End Using
End Using
End If
Next
columnnum = -1
For Each column In ds2.Tables(0).Columns
columnnum = columnnum + 1
columname = ds2.Tables(0).Columns(columnnum).ColumnName
If Not ds.Tables(0).Columns.Contains(columname) Then
MessageBox.Show("Will Delete " & columname)
Dim SqlDelCol As String = "ALTER TABLE MasterTrainerSchedule DROP COLUMN [" & columname.Trim() & "]"
Using con As New OleDbConnection(cs)
Using cmd As New OleDbCommand(SqlDelCol, con)
con.Open()
cmd.ExecuteNonQuery()
End Using
End Using
End If
Next
ds2.Tables.Clear()
da2 = New OleDbDataAdapter(sql, cs)
da2.Fill(ds2)
End Function`

Answer 1

I don't know very many details of what you are doing here but here is an example of a more normalized approach to this.
create table Trainers
(
TrainerID int identity
, FirstName varchar(25)
, LastName varchar(25)
, CONSTRAINT PK_Trainers PRIMARY KEY CLUSTERED (TrainerID)
)
create table Courses
(
CourseID int identity
, CourseName varchar(50)
, CONSTRAINT PK_Courses PRIMARY KEY CLUSTERED (CourseID)
)
create table TrainerCourses
(
TrainerID int not null
, CourseID int not null
, StartDate date not null
, EndDate date not null
, DailyStartTime time not null
, CONSTRAINT PK_TrainerCourses PRIMARY KEY CLUSTERED (TrainerID, CourseID, StartDate, DailyStartTime)
, CONSTRAINT FK_TrainerCourses_Trainers FOREIGN KEY (TrainerID) REFERENCES Trainers(TrainerID)
, CONSTRAINT FK_TrainerCourses_Courses FOREIGN KEY (CourseID) REFERENCES Courses(CourseID)
)