Which of the following is the correct syntax to combine two SELECT queries using UNION ALL in PostgreSQL?

easy📝 Syntax Q12 of 15

PostgreSQL - Set Operations and Advanced Queries

Which of the following is the correct syntax to combine two SELECT queries using UNION ALL in PostgreSQL?

ASELECT name FROM students UNION ALL SELECT name FROM teachers;

BSELECT name FROM students UNIONALL SELECT name FROM teachers;

CSELECT name FROM students UNION ALL FROM teachers;

DSELECT name FROM students UNION ALL SELECT name FROM teachers WHERE;

Step-by-Step Solution

Solution:

Step 1: Check the correct keyword spacing
The correct keyword is UNION ALL with a space between UNION and ALL.
Step 2: Verify the SELECT statements are complete
Both queries must be valid SELECT statements with matching column counts and types.
Final Answer:
SELECT name FROM students UNION ALL SELECT name FROM teachers; -> Option A
Quick Check:
Correct syntax uses 'UNION ALL' with space [OK]

Quick Trick: Use space between UNION and ALL, both queries must be valid [OK]

Common Mistakes:

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