1Z0-006 Database Concepts & Terminology

Question 1

Which SQL clause is used to remove duplicate rows from a query result?

Accepted Answer

DISTINCT

Answer

GROUP BY

Answer

UNIQUE

Answer

ORDER BY

Question 2

In a relational database, a PRIMARY KEY constraint ensures that:

Accepted Answer

Each row has a unique, non‑NULL identifier

Answer

A column may contain duplicate values

Answer

The column is always indexed but can be NULL

Answer

Rows are physically stored in sorted order

Question 3

Which normal form eliminates partial dependencies on a composite primary key?

Accepted Answer

Second Normal Form

Answer

First Normal Form

Answer

Third Normal Form

Answer

Boyce‑Codd Normal Form

Question 4

The ANSI SQL data type that stores variable‑length character strings up to a defined limit is:

Accepted Answer

VARCHAR

Answer

CHAR

Answer

CLOB

Answer

NCHAR

Question 5

Which Oracle background process writes modified database buffers from the SGA to data files?

Accepted Answer

DBWn

Answer

LGWR

Answer

CKPT

Answer

PMON

Question 6

A FOREIGN KEY constraint enforces:

Accepted Answer

Referential integrity between tables

Answer

Entity integrity on the parent table

Answer

Unique values in a column

Answer

Automatic index creation only

Question 7

What does the acronym DML stand for in SQL?

Accepted Answer

Data Manipulation Language

Answer

Data Modeling Lab

Answer

Database Management Logic

Answer

Distributed Memory Layer

Question 8

In Oracle, which structure maps logical database blocks to physical file locations?

Accepted Answer

Extent map in segment header

Answer

Redo log

Answer

Control file

Answer

Parameter file

Question 9

Which command permanently saves all outstanding transactions in an Oracle database?

Accepted Answer

COMMIT

Answer

ROLLBACK

Answer

SAVEPOINT

Answer

FLASHBACK