Check out example codes for "There is already an open DataReader associated with this Command which must be closed first c#". It will help you in understanding the concepts better.

Code Example 1

<connectionStrings>
    <add name="IdentityConnection" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=|DataDirectory|\IdentityDb.mdf;Integrated Security=True;MultipleActiveResultSets=true;" providerName="System.Data.SqlClient" />
  </connectionStrings>

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