efficient way to check if at least one row contains a null value in a DataView ?

Question

Hi everybody,

I need to do a test in a DataView to check if at least one row contains one cell with a null value. What is the best way to do it in your opinion ?

Thanks in advance.

Answer 1

Without measuring, I would guess that the answer is a nested loop.

Answer 2

As SLaks mentioned, you're going to need to loop over the rows and the items in each row. You can do this with LINQ like this:

bool hasNull = view.Table.Rows.OfType<DataRow>()
    .Any(r => r.ItemArray.Any(o => o == DBNull.Value));

Or you can write the loop yourself, something like:

private bool HasEmptyItem(DataView view)
{
    foreach (DataRow row in view.Table.Rows)
    {
        foreach (DataColumn col in view.Table.Columns)
        {
            if (row[col] == DBNull.Value)
                return true;
        }
    }
    return false;
}

While the LINQ version is a lot more compact, it's still going to loop over the rows and columns, so take your pick.

Update: Based on comments, here's a better sample based on what you're trying to do. This simply loops over the rows, and checks if a give column is null (make sure to use DBNull.Value with a DataTable), and if so, just sets it to false to prevent problems in your case. Just change IS_DEFAULT_COL to be the correct index.

const int IS_DEFAULT_COL = 1;
foreach (DataRow row in view.Table.Rows)
{
    if (row[IS_DEFAULT_COL] == DBNull.Value)
        row[IS_DEFAULT_COL] = false;
}