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Manuals / SQL / Checkpoint 5

A · Query · beginner · Gate · Week 3–4 · Checkpoint 5 of 12

Checkpoint A — SELECT & JOINs

Before aggregations and mutations, prove you can read relational data with filters and joins. Fix gaps before Phase B.

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Step 1 of 3

Pass criteria

All six must be true. Fix failures before GROUP BY chapter.

  • 10+ saved queries in sql-notes/queries/ with descriptive filenames
  • SCHEMA.md documents all sandbox tables and relationships
  • WHERE query with AND/OR, NULL check, and LIKE pattern
  • INNER JOIN and LEFT JOIN each used correctly
  • Anti-join query: rows in A with no match in B (LEFT JOIN + IS NULL)
  • Can draw a 3-table ER diagram and explain join keys aloud
Pass criteriaDrag stickies · tap for tips
Study mapDrag stickies · tap for tipsKeep it shortdrag · tap →Name the waitdrag · tap →Scope locatorsdrag · tap →Trace when stuckdrag · tap →One browser firstdrag · tap →Isolate statedrag · tap →Assert the UIdrag · tap →Retry wiselydrag · tap →Seed datadrag · tap →Close the loopdrag · tap →Keep it shortdrag · tap →Name the waitdrag · tap →Scope locatorsdrag · tap →Trace when stuckdrag · tap →One browser firstdrag · tap →Isolate statedrag · tap →Pathwise hackdrag · tap →Pass criteriadrag · tap →Try thisdrag · tap →Follow the dashed drag · tap →

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Audit sql-notes repo. Mark pass/fail in README.

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Write query verifying: every order has a valid customer_id. What result means bug?