• No, SQL Server does not do reliable position-based short circuiting of expressions. The order things will be evaluated in depends on indexes, data distribution, estimated row counts and whatever plan the optimiser comes up with.

    I would imagine both of those queries do 7 reads because they're scanning the entire table (or maybe scanning an index). Without table defs and index defs impossible to say for sure.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

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