Should I call SqlDataReader.HasRows if I am calling SqlReader.Read

c# sql .net methods sqldatareader
Joshua Volearix picture Joshua Volearix · Jan 7, 2013 · Viewed 44k times · Source

Trying to see if it is beneficial to add an if (dr.HasRows) before the while (dr.read()) function. I mean, technically if it doesn't have rows it isn't going to read, so would it matter if you checked this first?

using (SqlDataReader dr = cmd.ExecuteReader())
{
    if (dr.HasRows)
    {
        while (dr.Read())
        {
            ....do stuff here
        }
    }
}

or is this going to essentially do the exact same thing if you're just making sure it has values to provide...

using (SqlDataReader dr = cmd.ExecuteReader())
{
    while (dr.Read())
    {
        ....do stuff here
    }
}

Answer

Vishal Suthar picture Vishal Suthar · Jan 7, 2013

No..It is not mandatory to check (dr.HasRows) if the DataReader contains any row or not.

Read() will return False if there are no more rows to fetch, but Reader.HasRows is much more telling as to what it does than Read() so it would be a good practice to use Reader.HasRows because you may accidentally do something other than Read() which may fall into exception.

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