CODEWITHSUNDEEP
c#datatable
Happy
Happy

Reputation: 1145

removing few columns from data table C#

I need to remove few columns from datatable and bind to grid view. So I tried below code:

        obj_dt = obj_backup.sale_where_date();

        grd_excel.DataSource = obj_dt;

        obj_dt_pdf = obj_dt;

        // to remove few columns in data table 

        obj_dt_pdf.Columns.Remove("Location");
        obj_dt_pdf.Columns.Remove("No Opn Stack");
        obj_dt_pdf.Columns.Remove("Expiry Date");
        obj_dt_pdf.Columns.Remove("Discount %");
        obj_dt_pdf.Columns.Remove("Discount Amt");
        obj_dt_pdf.Columns.Remove("TAX");
        obj_dt_pdf.Columns.Remove("VAT");
        obj_dt_pdf.Columns.Remove("Entry Date");

        dataGridView_wd_pdf.DataSource = obj_dt_pdf;

Problem is after removing columns in obj_dt_pdf its also removing from obj_dt. I need to remove in obj_dt_pdf alone.
where I made error?

Upvotes: 4

Views: 846

Answers (4)

musefan
musefan

Reputation: 48465

DataTable is a class, and classes are "reference types", this means that when you assign it to another variable you just have two variables pointing to the same instance.

You would need to create a "copy" of the object, and lucky for you it just so happens that DataTable has a Copy() method, so you can do this:

obj_dt_pdf = obj_dt.Copy();

Do not get this confused with the Clone() method, which will only include the structure, and not the data

Upvotes: 0

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236328

When you are assigning obj_dt to obj_dt_pdf you are not copying DataTable - you just make copy of reference to DataTable instance. So, that makes both variables point to same DataTable instance:

obj_dt_pdf = obj_dt;

Create copy of DataTable instead (use DataTable.Copy() method to copy both table structure and data):

obj_dt_pdf = obj_dt.Copy();

Now obj_dt_pdf points to copy of original DataTable, and changes of copy will not affect original DataTable instance.

Upvotes: 0

Mike Perrenoud
Mike Perrenoud

Reputation: 67948

You need to use Copy, so something like this:

obj_dt_pdf = obj_dt.Copy();

instead of this:

obj_dt_pdf = obj_dt;

The Copy method will copy both the structure and the data.

Upvotes: 0

Tim Schmelter
Tim Schmelter

Reputation: 460380

Then don't use the same reference. You can use Clone to get a DataTable with the same schema of a table (without data) or Copy to create a clone with all data:

obj_dt = obj_backup.sale_where_date();
var copy = obj_dt.Copy();
copy.Columns.Remove("Location");
copy.Columns.Remove("No Opn Stack");
// ...
dataGridView_wd_pdf.DataSource = copy;

Upvotes: 1

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