Checking for duplicates on a Grid

I recently used this snippit of code and found it useful. I wanted to post it here so I had it for future reference. Credit:

/* Check for data duplicates on a grid. */
Local Row &row1, &row2;
Local number &r, &r1;

&rs = GetLevel0().GetRow(1).GetRowset(Scroll.grid_table);

For &r = 1 To &rs.ActiveRowCount
/*Get grid row*/
&row1 = &rs.GetRow(&r);
/*once we have a row, we are going to loop through the grid rows and make sure a specific field value is unique*/
For &r1 = 1 To &rs.ActiveRowCount
&row2 = &rs.GetRow(&r1);
/* if this is a different row, and the field_name value matches then throw an error*/
If &r1 <> &r And
&row1.grid_table.field_name.Value = &row2.grid_table.field_name.Value Then
MessageBox(0, "", 0, 0, "Error. Duplicate values are not allowed.");