DataReader already open error when trying to run two queries

Solution 1:

By default it´s not possible to have two SqlDataReader's open at the same time sharing the same SqlConnection object. You should close the first one (queryInvestorLookup) before calling the second (queryPasswordCheck).

This would be good from a design and performance point of view since a recommendation for .NET is that every unmanaged resource (like database access) is opened as later as possible and closed early as possible.

Another way would be to enable MARS but afaik it is only available for Sql2005 and up.

The third solution would be to use the same SqlDataReader to issue the two queries and then navigate through then using NextResults() method.