Q$1.$ Choose the correct answer from the following

$2\mathrm{.}2$

In order for two queries to be UNION$-$compatible, they must:

A$)$ both have the same number of lines in their SQL statements.

B$)$ both output compatible data types for each column and return the same number of rows.

C$)$ both return at least one row.

D$)$ both return exactly one row.

Answer:

$2.$ The UNION clause is used to:

A$)$ combine the output from multiple queries into a single result table.

B$)$ join two tables together to form one table.

C$)$ find all rows that do not match in two tables.

D$)$ find all rows that are in one table, but not the other.

Answer:

$3.$ A join in which the joining condition is based on equality between values in the common columns is called a$($n$)$:

A$)$ equi$-$join.

B$)$ unilateral join.

C$)$ natural join.

D$)$ both A and $C.$

Answer:

$4.$ A type of query that is placed within a WHERE or HAVING clause of another query is called a:

A$)$ master query.

B$)$ subquery.

C$)$ superquery,

D$)$ multi$-$query.

Answer: