Question

Union operation in relational databases

a) Create a new data table with selected fields from the original one
b) Combines two data tables with same fields
c) Creates a subset of data removing some of the records and cases
d) Creates a new table with only the common cases of the input tables

Answer 1

The union operation in relational databases combines two data tables with the same fields into a single unique set, eliminating duplicates.

Step-by-step explanation:

The union operation in relational databases is used to combine two data tables with the same fields. This operation takes all the records from both tables and merges them into a single table, eliminating duplicates to ensure that only unique rows are present in the result set. It is important to note that the tables being unioned must have the same number of columns and the corresponding columns must have compatible data types. The correct answer is (b) Combines two data tables with same fields. The other options listed do not correspond with the functionality of the union operation in relational databases.