sqlfmt▍
sqlfmt blog
Practical posts on writing cleaner SQL and fixing the errors your database gives back.
By Sharon Ben-Moshe · Aug 16, 2026
Use BigQuery QUALIFY to filter window-function results without an outer subquery. Learn evaluation order, top-N-per-group patterns, and portability.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
Learn to read PostgreSQL EXPLAIN ANALYZE: estimated versus actual rows, scan types, safe use with writes, and a repeatable tuning workflow.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
GROUP BY collapses rows; window functions retain detail and add calculations beside it. See when each approach fits, with clear SQL examples.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
UNION removes duplicate rows; UNION ALL keeps every row. Learn compatibility rules, ordering scope, and how to choose the correct set operator.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
WHERE filters rows before aggregation; HAVING filters grouped results. Learn where each clause belongs with a practical sales-report example.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
INNER JOIN keeps matches; LEFT JOIN also retains unmatched left rows. See the result difference, the WHERE-clause trap, and safe examples.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
EXISTS checks for matching rows; IN compares against a list. Learn the practical differences, the NOT IN NULL trap, and when to use each.
Read postBy Sharon Ben-Moshe · Aug 16, 2026
COUNT(*) counts rows; COUNT(column) skips NULLs. See the exact difference, join behavior, COUNT(DISTINCT), and reliable SQL examples.
Read postBy Sharon Ben-Moshe · Aug 8, 2026
Every major SQL dialect can insert-or-update in one statement, but the syntax is different everywhere — ON CONFLICT, ON DUPLICATE KEY UPDATE, INSERT OR REPLACE, and MERGE all solve the same problem in incompatible ways.
Read postBy Sharon Ben-Moshe · Aug 8, 2026
MySQL's Error 1146 (“Table '...' doesn't exist”) almost always comes down to a missing database prefix, a case mismatch on a case-sensitive filesystem, or a table that never actually got created. Here's how to tell which.
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