{"slug":"sql-ops","title":"sql-ops","summary":"Quick reference for common SQL patterns, CTEs, window functions, and indexing strategies. Triggers on: sql patterns, cte example, window functions, sql join, index strategy, pagination sql.","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-09-30T19:36:56.619883Z","repo":{"url":"https://github.com/0xDarkMatter/claude-mods","stars":43,"forks":7,"license":"MIT","updatedAt":"2026-09-30T15:18:48Z"},"bodyHtml":"
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name: sql-ops\ndescription: \"Quick reference for common SQL patterns, CTEs, window functions, and indexing strategies. Triggers on: sql patterns, cte example, window functions, sql join, index strategy, pagination sql.\"\nlicense: MIT\nallowed-tools: \"Read Write\"\nmetadata:\nauthor: claude-mods\nrelated-skills: postgres-ops, sqlite-ops

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SQL Patterns

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Quick reference for common SQL patterns.

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CTE (Common Table Expressions)

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WITH active_users AS (\n    SELECT id, name, email\n    FROM users\n    WHERE status = 'active'\n)\nSELECT * FROM active_users WHERE created_at > '2024-01-01';\n
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Chained CTEs

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WITH\n    active_users AS (\n        SELECT id, name FROM users WHERE status = 'active'\n    ),\n    user_orders AS (\n        SELECT user_id, COUNT(*) as order_count\n        FROM orders GROUP BY user_id\n    )\nSELECT u.name, COALESCE(o.order_count, 0) as orders\nFROM active_users u\nLEFT JOIN user_orders o ON u.id = o.user_id;\n
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Window Functions (Quick Reference)

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FunctionUse
ROW_NUMBER()Unique sequential numbering
RANK()Rank with gaps (1, 2, 2, 4)
DENSE_RANK()Rank without gaps (1, 2, 2, 3)
LAG(col, n)Previous row value
LEAD(col, n)Next row value
SUM() OVERRunning total
AVG() OVERMoving average
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SELECT\n    date,\n    revenue,\n    LAG(revenue, 1) OVER (ORDER BY date) as prev_day,\n    SUM(revenue) OVER (ORDER BY date) as running_total\nFROM daily_sales;\n
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JOIN Reference

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TypeReturns
INNER JOINOnly matching rows
LEFT JOINAll left + matching right
RIGHT JOINAll right + matching left
FULL JOINAll rows, NULL where no match
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Pagination

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-- OFFSET/LIMIT (simple, slow for large offsets)\nSELECT * FROM products ORDER BY id LIMIT 20 OFFSET 40;\n\n-- Keyset (fast, scalable)\nSELECT * FROM products WHERE id > 42 ORDER BY id LIMIT 20;\n
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Transaction Isolation Levels

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LevelDirty ReadNon-Repeatable ReadPhantom ReadUse
READ UNCOMMITTEDPossiblePossiblePossibleRarely (PostgreSQL treats as READ COMMITTED)
READ COMMITTEDNoPossiblePossibleDefault in most databases
REPEATABLE READNoNoPossible*Consistent multi-statement reads
SERIALIZABLENoNoNoCritical invariants (retry on serialization failure)
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*PostgreSQL's REPEATABLE READ also prevents phantoms via snapshot isolation.

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BEGIN TRANSACTION ISOLATION LEVEL SERIALIZABLE;\n-- ... critical operations ...\nCOMMIT;  -- be prepared to retry on serialization failure\n
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Keep the default READ COMMITTED globally; raise the level per-transaction only where the logic requires it.

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Index Quick Reference

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Index TypeBest For
B-treeRange queries, ORDER BY
HashExact equality only
GINArrays, JSONB, full-text
CoveringAvoid table lookup
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Anti-Patterns

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MistakeFix
SELECT *List columns explicitly
WHERE YEAR(date) = 2024WHERE date >= '2024-01-01'
NOT IN with NULLsUse NOT EXISTS
N+1 queriesUse JOIN or batch
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Additional Resources

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For detailed patterns, load:

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