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Union vs Union All

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Union vs Union All

If you can teach Union vs Union All using 2024 + 2025 names, you know it. If you only know the heading, you don’t.

Do Union vs Union All once by hand. UNION / UNION ALL. Change one input. Say the new result out loud.

Skip Union vs Union All and UNION ALL when you needed distinct shows up in two year tables.

Priya ships Union vs Union All in two year tables. That is the use case worth saying.

Don’t do this with Union vs Union All — UNION ALL when you needed distinct. Interviewers spot it in ten seconds.

Place Union vs Union All next to nearby SQL work — UNION / UNION ALL is the link.

Close Union vs Union All with: “If I skip it, 2024 + 2025 names goes wrong like this: UNION ALL when you needed distinct.”

Exam tip

For Union vs Union All: definition + two year tables + one failure.

Union vs Union All — sample query

CREATE TABLE a (id INTEGER, label TEXT);
CREATE TABLE b (id INTEGER, label TEXT);
INSERT INTO a VALUES (1, 'x'), (2, 'y');
INSERT INTO b VALUES (2, 'y'), (3, 'z');
SELECT label FROM a
UNION
SELECT label FROM b;

Union vs Union All — uNION merges result sets and drops duplicate rows.

Short notes

DefUnion vs Union All — Priya uses it for 2024 + 2025 names in two year tables.
RuleUnion vs Union All → UNION / UNION ALL.
RememberUnion vs Union All + the query planner (two year tables).
UseUnion vs Union All in two year tables (2024 + 2025 names).
TrapUnion vs Union All — UNION ALL when you needed distinct.
ExUnion vs Union All → 2024 + 2025 names.

CREATE TABLE a (id INTEGER, label TEXT); CREATE TABLE b (id INTEGER, label TEXT); INSERT INTO a VALUES (1, 'x'), (2, 'y'); INSERT INTO b VALUES (2, 'y'), (3, 'z'); SELECT label FROM a UNION SELECT label FROM b;

Union vs Union All

Union vs Union All — sample query

Short notes

Questions

Union vs Union All

Union vs Union All — sample query

Short notes

Questions