Check for column name in a SqlDataReader object

c# .net sqldatareader
Michael Kniskern picture Michael Kniskern · Dec 17, 2008 · Viewed 155.5k times · Source

How do I check to see if a column exists in a SqlDataReader object? In my data access layer, I have create a method that builds the same object for multiple stored procedures calls. One of the stored procedures has an additional column that is not used by the other stored procedures. I want to modified the method to accommodate for every scenario.

My application is written in C#.

Answer

Chad Grant picture Chad Grant · May 2, 2009 
public static class DataRecordExtensions
{
    public static bool HasColumn(this IDataRecord dr, string columnName)
    {
        for (int i=0; i < dr.FieldCount; i++)
        {
            if (dr.GetName(i).Equals(columnName, StringComparison.InvariantCultureIgnoreCase))
                return true;
        }
        return false;
    }
}

Using Exceptions for control logic like in some other answers is considered bad practice and has performance costs. It also sends false positives to the profiler of # exceptions thrown and god help anyone setting their debugger to break on exceptions thrown.

GetSchemaTable() is also another suggestion in many answers. This would not be a preffered way of checking for a field's existance as it is not implemented in all versions (it's abstract and throws NotSupportedException in some versions of dotnetcore). GetSchemaTable is also overkill performance wise as it's a pretty heavy duty function if you check out the source.

Looping through the fields can have a small performance hit if you use it a lot and you may want to consider caching the results.

Related questions

Multiples Table in DataReader

I normally use DataSet because It is very flexible. Recently I am assigned code optimization task , To reduce hits to the database I am changing two queries in a procedure. one Query returns the count and the other returns the …

Read More
How to read multiple resultset from SqlDataReader?

I have a SP from that I am trying to return 2 result set from, and in my .cs file i am trying something like this: dr = cmd.ExecuteReader(); while (dr.Read()) { RegistrationDetails regDetails = new RegistrationDetails() { FName = dr["FName"].ToString(), LName = …

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

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 …

Read More