Do not let insert same value in a Datagridview C#

Question

I own a DataGridView where I have a column called Ramal, where the specific seller’s extension will go.

How to do that when I type in a line an existing extension, appear a message that cannot be inserted? As an example below:

Answer 1

Go to your event DataGridView and choose the option CellEndEdit.

Within this event method enter the following code:

private void dataGridView1_CellEndEdit(object sender, DataGridViewCellEventArgs e)
{
    string v = this.dataGridView1[e.ColumnIndex, e.RowIndex].Value?.ToString().Trim();
    foreach (DataGridViewRow row in this.dataGridView1.Rows)
    {
        if (row.Index >= this.dataGridView1.Rows.Count - 1) break;
        if (row.Cells[3].Value?.ToString().Trim() == v && row.Index != e.RowIndex)
        {
            MessageBox.Show("Opa, já existe um ramal igual a esse");
            this.dataGridView1[e.ColumnIndex, e.RowIndex].Value = null;
            break;
        }
    }
}

Cells[3] is the column where the branches are located.

When someone type an extension that already exists in the column, the message will appear.

Answer 2

The ideal events for such validation are Columnchanged and Rowchanged. Columnchanged occurs soon after the user has changed the value of a column is ideal for column-by-column validation. Rowchanged occurs after that the user has completed the change in line.