1Z0-006 Relational Data Model 4

Question 1

Which type of key is a system-generated unique identifier (such as a sequence value) with no business meaning?

Accepted Answer

Surrogate key

Answer

A surrogate key is an artificially generated identifier (e.g., from an Oracle SEQUENCE) that has no inherent business meaning.

Question 2

What does cardinality describe in the context of a database table?

Accepted Answer

The number of rows in the table

Answer

Cardinality refers to the number of rows (tuples) currently in a relation (table).

Question 3

Which SQL clause is used to filter groups after a GROUP BY has been applied?

Accepted Answer

HAVING

Answer

The HAVING clause filters grouped results after aggregation, while WHERE filters individual rows before grouping.

Question 4

In a relational table, what is a tuple?

Accepted Answer

A single row of data

Answer

In relational theory, a tuple corresponds to a single row in a table, representing one complete record.

Question 5

Which type of JOIN returns all rows from the left table and matching rows from the right table, with NULLs for unmatched right rows?

Accepted Answer

LEFT OUTER JOIN

Answer

A LEFT OUTER JOIN includes all rows from the left table; where no match exists in the right table, NULL values are returned for right-table columns.

(1Z0-006) Oracle Database Foundations Associate Practice Test