[Solved] Which rule must be followed when using SQL set operations like UNION or INTERSECT? — Ans: Both queries must have the same number of columns with compatible data types. | SQL

SQL - Set Operations

Which rule must be followed when using SQL set operations like UNION or INTERSECT?

ABoth queries must have the same number of columns with compatible data types.

BThe second query must have more columns than the first.

CColumn names must be identical in both queries.

DSet operations only work with numeric columns.

Step-by-Step Solution

Solution:

Step 1: Understand set operation requirements
Set operations combine results from multiple queries, so columns must match in number and type to align data correctly.
Step 2: Check column name and type rules
Column names do not need to match; only the first query's column names are used. Data types must be compatible, and the number of columns must be the same.
Final Answer:
Both queries must have the same number of columns with compatible data types. -> Option A
Quick Check:
Column count and type compatibility = A [OK]

Quick Trick: Match column count and types for set operations [OK]

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Which rule must be followed when using SQL set operations like UNION or INTERSECT?