SQL Queries Don't Run in the Order You Write Them — Here's Why It Matters

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Although SQL queries are written starting with SELECT, databases process them in a different sequence that affects both results and performance. The actual execution order follows these steps: FROM, WHERE, GROUP BY, HAVING, SELECT, DISTINCT, ORDER BY, and finally LIMIT or OFFSET. Early stages like FROM and WHERE handle table selection and row filtering, which can significantly reduce the data processed in later steps. HAVING differs from WHERE in that it filters grouped results rather than individual rows. Understanding this execution order helps developers write more efficient queries and troubleshoot unexpected outputs.

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