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Queries Inside Queries: PostgreSQL: Uncharted

Courses PostgreSQLQueries Inside Queries

Queries Inside Queries

Nest focused queries, test related sets, and combine compatible results into precise reports.

PostgreSQL
Unit 9 of 12
10 lessons
94 min
220 XP

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Lessons

10 total

1A Query as a ValueUse a scalar subquery as the comparison value in a larger query.CodeConcept8 min20 XPOpen
2IN and NOT INFilter rows by membership in the result of a subquery.CodeConcept9 min20 XPOpen
3EXISTSUse EXISTS and NOT EXISTS to test whether related rows are present.CodeConcept9 min20 XPOpen
4Correlated SubqueriesCompare each outer row with a summary calculated for its own category.CodeConcept10 min20 XPOpen
5A Query in FROMBuild and filter an aggregate derived table in the FROM clause.CodeConcept9 min20 XPOpen
6Join or Subquery?Choose between a join and a subquery based on the shape of the needed result.InteractiveConcept7 min20 XPOpen
7Stacking Results: UNIONCombine compatible result sets while controlling duplicate removal.CodeConcept9 min20 XPOpen
8INTERSECT and EXCEPTFind shared and remaining rows with INTERSECT and EXCEPT.CodeConcept10 min20 XPOpen
9Subquery WorkoutUse correlated existence tests to find overdue loans and untouched books.CodePractice11 min20 XPOpen
10Subqueries Mastery CheckCombine scalar, membership, correlated, and set queries in one staff-and-customer list.CodeMastery check12 min40 XPOpen

Changing Data Readable Queries with CTEs