• Here's the query generated by your very strange code:

    Select @retvalOUT = Convert(TinyInt,Sunday)

    from [dbo].[SLADCSchedule]

    where ScheduleStart <= 'Apr 1 2012 12:00AM'

    and ScheduleEnd >= 'Apr 1 2012 12:00AM'

    and BranchID = 99

    What's this supposed to do?

    Convert(TinyInt,Sunday)

    “Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw

    For fast, accurate and documented assistance in answering your questions, please read this article.
    Understanding and using APPLY, (I) and (II) Paul White
    Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden