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SQL Fundamentals

Group Results with GROUP BY and HAVING

Group rows by meaningful keys, aggregate within each group, filter summaries with HAVING, and verify that detail-level and group-level predicates stay separate.

Beginner14 min read
SQL Fundamentals lessonRelational data foundationsPractice

UNTIMED COACHING

Practice before the pressure

Use feedback to correct the model, not merely memorize an option position.

GUIDED PRACTICE

Practice the lesson questions

Answer normal lesson questions without a timer. Every answer includes an explanation, and incorrect answers can be tried again before continuing.

CONCEPT MODELS

See the lesson as a system

Use these visual guides to connect the key ideas before answering the questions.

Connect the roles in Group Results with GROUP BY and HAVINGKeep grouping key, row groups, group aggregate, and having condition as separate roles.
Connect the roles in Group Results with GROUP BY and HAVINGA topic-specific model connects four distinct roles used to reason about group results with group by and having.
Grouping valueData identifies each technician group
Table groupsTable partitions rows by technician key
Aggregate resultResult counts rows inside each group
Having conditionDecision filters completed group summaries
Verify Group verificationConnect group verification with its topic-specific inspection, expected outcome, and protected database boundary.
Verify Group verificationA verification model for group results with group by and having connects the final data decision to its check, result, and protected boundary.
Output evidenceEvidence reconciles source rows and groups
Starting checkReview output evidence
Expected resultConfirm output evidence
Safety boundaryDo not validate only the largest group