Multiple choice technology databases

The UNION operator is used to combine the result-set of two or more SELECT statements when

  1. each SELECT statement within the UNION has the same number of columns

  2. The columns have similar data types

  3. the columns in each SELECT statement are in same order.

  4. None
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

UNION combines results from multiple SELECT statements into one result set. SQL requires all SELECTs in a UNION to have identical column count, compatible data types in each position, and the same column order. These structural rules ensure rows can be stacked vertically.

Keep practicing — related questions