How to convert this String-based sql query to use Linq - sql

Question

I have the following routine (that works) but which is messy to update owing to the hand-typed strings it uses:
Private Sub ListDefaults()
Dim conn As New SqlConnection( _
"server=bas047\AUTODESKVAULT;Database=DWGDetails;Integrated Security=SSPI")
'Dim conn As New SqlConnection( _
'"server=bas047\AUTODESKVAULT;Database=DWGDetails;Integrated Security=SSPI")
Try
'clear columns
If Not Me.DataGridView1.DataSource Is Nothing Then
Me.DataGridView1.Columns.Clear()
Me.DataGridView1.DataSource = Nothing
End If
conn.Open()
Dim cmd As SqlCommand = conn.CreateCommand()
Dim DLcmd As SqlCommand = conn.CreateCommand()
Dim ILcmd As SqlCommand = conn.CreateCommand()
'Dim srctbl As String = String.Empty
If RadioButton1.Checked = True Then 'A3
shtsize = "A3"
cmd.CommandText = "SELECT [AttributeName],[IsDefaultValue],[DefaultValue] FROM " & _
Chr(34) & "DefaultValues(Borders SB-A3_993-5.2(block))" & Chr(34)
srctbl = "DefaultValues(Borders SB-A3_993-5.2(block))"
ElseIf RadioButton2.Checked = True Then 'A2
shtsize = "A2"
cmd.CommandText = "SELECT [AttributeName],[IsDefaultValue],[DefaultValue] FROM " & _
Chr(34) & "DefaultValues(Borders SB-A2_992-5.2(block))" & Chr(34)
srctbl = "DefaultValues(Borders SB-A2_992-5.2(block))"
ElseIf RadioButton3.Checked = True Then 'A1
shtsize = "A1"
cmd.CommandText = "SELECT [AttributeName],[IsDefaultValue],[DefaultValue] FROM " & _
Chr(34) & "DefaultValues(Borders SB-A1_991-5.2(block))" & Chr(34)
srctbl = "DefaultValues(Borders SB-A1_991-5.2(block))"
ElseIf RadioButton4.Checked = True Then 'A0
shtsize = "A0"
cmd.CommandText = "SELECT [AttributeName],[IsDefaultValue],[DefaultValue] FROM " & _
Chr(34) & "DefaultValues(Borders SB-A0_990-5.2(block))" & Chr(34)
srctbl = "DefaultValues(Borders SB-A0_990-5.2(block))"
End If
'Populate datagridview1
da = New SqlDataAdapter(cmd.CommandText, conn.ConnectionString)
ds = New DataSet
da.Fill(ds, srctbl)
DataGridView1.DataSource = ds.Tables(0)
DataGridView1.AutoResizeColumns(DataGridViewAutoSizeColumnsMode.DisplayedCells)
'should enable setting of the date and drawn by entries
'Dim X As Integer
'For X = 0 To DataGridView1.Rows.Count
' If UCase(DataGridView1.Rows(X).Cells(0).Value) = "DRAWN BY" Then
' MessageBox.Show("Found Drawn by!")
' End If
'Next
Catch ex As System.Data.SqlClient.SqlException
MessageBox.Show("There was an error in executing the SQL." & vbLf & "Error Message:" & ex.Message, "SQL")
Finally
'cleanup and reset!
conn.Close()
End Try
End Sub
And I am thinking this is an ideal candidate for Linq. This is what I have so far that seems to work:
Private Sub ListDefaultsMk1()
Try
Using db As New DWGDetailsDataContext
If RadioButton1.Checked = True Then 'A3
shtsize = "A3"
DataGridView1.DataSource =
From c In db.DefaultValues_Borders_SB_A3_993_5_2_block__s()
Select New With {c.AttributeName, c.IsDefaultValue, c.DefaultValue}
ElseIf RadioButton2.Checked = True Then 'A2
shtsize = "A2"
DataGridView1.DataSource =
From c In db.DefaultValues_Borders_SB_A2_992_5_2_block__s()
Select New With {c.AttributeName, c.IsDefaultValue, c.DefaultValue}
ElseIf RadioButton3.Checked = True Then 'A1
shtsize = "A1"
DataGridView1.DataSource =
From c In db.DefaultValues_Borders_SB_A1_991_5_2_block__s()
Select New With {c.AttributeName, c.IsDefaultValue, c.DefaultValue}
ElseIf RadioButton4.Checked = True Then 'A0
shtsize = "A0"
DataGridView1.DataSource =
From c In db.DefaultValues_Borders_SB_A0_990_5_2_block__s()
Select New With {c.AttributeName, c.IsDefaultValue, c.DefaultValue}
End If
End Using
Catch ex As Exception
MessageBox.Show("There was an error in executing the SQL." & vbLf & "Error Message:" & ex.Message, "SQL")
End Try
End Sub
The next step of my program is to take the (edited) values from the datagridview (In the case of the handwritten SQL code, the shared DataSet "ds") and populate another table but I can't figure out how to do that using Linq.
Can anyone offer assistance?
Thanks in advance,
Alex.
EDIT: Here's what I've reduced it to based on the comment
Private Sub ListDefaultsMk1()
Try
Using db As New DWGDetailsDataContext
If RadioButton1.Checked = True Then 'A3
shtsize = "A3"
DataGridView1.DataSource = (From c In db.DefaultValues_Borders_SB_A3_993_5_2_block__s Select c).ToList()
ElseIf RadioButton2.Checked = True Then 'A2
shtsize = "A2"
DataGridView1.DataSource = (From c In db.DefaultValues_Borders_SB_A2_992_5_2_block__s Select c).ToList()
ElseIf RadioButton3.Checked = True Then 'A1
shtsize = "A1"
DataGridView1.DataSource = (From c In db.DefaultValues_Borders_SB_A1_991_5_2_block__s Select c).ToList()
ElseIf RadioButton4.Checked = True Then 'A0
shtsize = "A0"
DataGridView1.DataSource = (From c In db.DefaultValues_Borders_SB_A0_990_5_2_block__s Select c).ToList()
End If
End Using
Catch ex As Exception
MessageBox.Show("There was an error in executing the Linq2SQL Query!" & vbLf & "Error Message:" & ex.Message, "SQL")
End Try
End Sub

Answer 1

Linq2Sql and DataSets are two completely different beasts and the reason you can both use them in a grid is because the grid can consume more types than just dataset.
You could technically pin down the linq query result using, say, ToList() and then bind the List to a grid. Afterwards all edits will be reflected on List which you can transform into other formats as you feel like (you didn't give much information about where the data should go other than its a table, table in dataset (must it be dataset), table in database, etc).