I'm making a WinForms application using VB.NET. I have a DataGridView that I am using to display results of a query to an SQL-Server Database. This works fine:
Dim SQL As New SqlConnection()
Dim CMD As New SqlCommand()
Dim ADP As New SqlDataAdapter()
Dim TBL As New DataTable()
SQL.Close()
SQL.ConnectionString = "Server=" & GetServerIP() & ";Database=" & GetDB() & ";User Id=" & userID & ";Password=" & pass & ";"
CMD.Connection = SQL
CMD.CommandText = "SELECT * FROM " & table
SQL.Open()
ADP.SelectCommand = CMD
TBL.Clear()
ADP.Fill(TBL)
DataGridView1.DataSource = TBL
The issue is that the DataGridView has a column NAME which is empty in every row.
I tried changing the query to SELECT SEQ_NUM FROM CONFIG_SYS
that resulted in a DataGridView with a NAME and SEQ_NUM column. I tried calling DataGridView1.Columns.Clear()
before the DataGridView1.DataSource = TBL
and that does not have an effect on anything. I should mention that if I query any table in my database that does not have a NAME column, I get the same results with an empty NAME column in my DataGridView.
My theory is that a DataGridView automatically adds NAME as the first column, expecting the Database Table to be set up with a NAME column as the primary key. However, my table does not have NAME, it has a column called SEQ_NUM as the primary key. I am able to work around this by doing DataGridView1.Columns("NAME").Visible = False
but I don't feel that this is the best way to do it.
Is there a better way to handle this - I'd like the column to not exist at all in the data grid, not just not be visible.
TBL.Clear()
incorrectly. Calling DataTable.Clear()
will clear the Data from a DataTable but it will leave the columns in place.
Instead I should have been calling TBL.Columns.Clear()
, which gets rid of the columns of the DataTable. However, using Breakpoints and Visual Studio's DataTable Visualizer I noticed that only calling TBL.Columns.Clear()
left the empty rows still in the DataTable. Therefore, to answer the question of how to get rid of a column in a DataGridView that you don't know why/how is there, I suggest to call:
DataTable.Clear()
DataTable.Columns.Clear()
Before setting your DataGridView equal to your DataTable.
The .Clear() Method of a DataTable Class "clears the DataTable of all data."
The DataTable.Columns Property gets "a DataColumnCollection that contains the collection of DataColumn objects for the table"
The DataColumnCollection Class also has a .Clear() Method which "clears the collection of any columns."
Thank you @TnTinMn for pointing me in the right direction by using breakpoints and @LarsTech for making me realize that I harshly mixed up DataGridView and DataTable in my original answer.
I hope this post can help others prevent themselves from ripping their hair out about where a non-existent column in their databases seemingly materialized from... If this does not fix your specific issue. I would also check the Query, Database Table setup, and the DataGridView; but for me the issue was with the DataTable.
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