• SELECT b.*

    FROM #tblBlocks b

    WHERE NOT EXISTS (

    SELECT 1

    FROM #tblBlocks bi

    WHERE bi.BlockID = b.BlockID

    AND bi.BaseStage = 1)

    “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