[Solved] Which of the following is the correct syntax to combine two SELECT queries using UNION? — Ans: SELECT col1 FROM table1 UNION SELECT col1 FROM table2; | SQL

SQL - Set Operations

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

ASELECT col1 FROM table1 UNION ALL JOIN SELECT col1 FROM table2;

BSELECT col1 FROM table1 JOIN SELECT col1 FROM table2;

CSELECT col1 FROM table1 WHERE UNION SELECT col1 FROM table2;

DSELECT col1 FROM table1 UNION SELECT col1 FROM table2;

Step-by-Step Solution

Solution:

Step 1: Review correct UNION syntax
The correct syntax is to write two SELECT statements separated by the UNION keyword.
Step 2: Identify invalid options
Options B, C, and D misuse JOIN or WHERE with UNION, which is incorrect syntax.
Final Answer:
SELECT col1 FROM table1 UNION SELECT col1 FROM table2; -> Option D
Quick Check:
UNION syntax = SELECT ... UNION SELECT ... [OK]

Quick Trick: UNION joins SELECTs directly, no JOIN or WHERE needed [OK]

Common Mistakes:

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