Which relational algebra operators can be applied to a pair of tables that are not union-compatible? explain on examples?

Solution:

Relational Algebra defines the theoretical foundation of manipulating

table content using the eight relational operators:

SELECT, PROJECT, JOIN, INTERSECT, UNION, DIFFERENCE, PRODUCT,

AND DIVIDE.

The relational operators have the property of closure that is applying

operators on relations produce relations.

1. SELECT, also known as RESTRICT, yields values for all the rows

found in a table that satisfy a given condition. SELECT yields a

horizontal subset of a table.

2. PROJECT yields all values for selected attributes. PROJECT yields a

vertical subset of a table

3. UNION: combines all rows from two or more tables, excluding

duplicate rows. In order to be used in a UNION, the tables must

have the same attribute characteristics, that it the attributes and

their domains must be compatible. When two or more tables

share the same number of columns and when their corresponding

columns share the same or compatible domains, they are said to

be union-compatible.

4. INTERSECT: yields only the rows that appear in both tables. As

with UNION, the tables must be union-compatible to yield valid

results.

This is the right answer.