What are the principles for writing an optimized sql query? [closed]

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If somebody has best Practices for Query Optimization, please write it as an answer.

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Last year I followed a series of videos by Andy Warren which I would highly recommend:

• Performance Tuning Puzzle - Part 1
• Performance Tuning Puzzle - Part 2
• Performance Tuning Puzzle - Part 3

Those are good, and he has a bunch more videos with great performance tips.

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learn how to analyze the execution plan.

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1. Pull data from the smallest tables first, then join to the larger ones.
2. Use INNER JOIN where you can.
3. Put conditions into the JOIN where possible, rather than in the WHERE clause.

These are very rough, not exhaustive, but rules of thumb that help me day-to-day.

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Check the MSDN blog of the Query optimization team and this list, both refers to SQL-Server