Query result set order issues in SQL Server

The order of the data cannot be guaranteed because the optimizer may choose to parallel processing or scan the data in a multi-file case without looking in order. The only order by is to ensure the sequence.

The process of parallel processing results in inconsistent sequencing, no parallelism on the single core, and dual cores, which may use parallel opportunities and fewer, and the result set order may vary on multiple cores on the server at a time.

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Query result set order issues in SQL Server