Data Dungeon
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Chamber 71 · Pattern Vault

Mirror Weave

CTE + LEFT JOIN

WITHLEFT JOINCOALESCEGROUP BY+480 XP
Locked

Clear the previous chamber to unlock this one. You can still preview the briefing.

Briefing

Every weaver must appear in the mirror — even those with no threads. COALESCE fills blank spools with zero.

Objective

Return weaver name and max_tension from WITH loom AS (weavers) LEFT JOIN threads, COALESCE(MAX(tension), 0), grouped by name.

Hint

WITH loom AS (SELECT id, name FROM weavers), LEFT JOIN threads, MAX + COALESCE, GROUP BY name.

Chamber schema

weavers2 cols

All vault weavers

idname
threads3 cols

Optional thread assignments

idweaver_idtension
chamber_71.sql

Results appear here after you run a query. Correct rows alone are not enough — the Warden must seal your loot.

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