Certification Questions

Q:

Which among the following keys are used to identify each row of the table uniquely?

A) Primary key B) Unique key
C) Partial key D) None of the above
 
Answer & Explanation Answer: A) Primary key

Explanation:

Primary key helps us to identify a row uniquely in a relation

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Q:

A column defined as UNIQUE can contain Nulls while a column defined as PRIMARY KEY can't contain Nulls

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:

Because a table can have only one primary key

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Q:

What is an Oracle index?

Answer

An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.

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Q:

What command would you use to create a backup control file?

Answer

Alter database backup control file to trace

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Q:

What is the maximum number of triggers, can apply to a single table?

A) 8 B) 10
C) 12 D) 14
 
Answer & Explanation Answer: C) 12

Explanation:

Maximim number of triggers that can be applied to a single table is 12

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Q:

Which command is used to return maximum value from result set?

A) MAX B) MIN
C) MAXIMUM D) MAXI
 
Answer & Explanation Answer: A) MAX

Explanation:

MAX command is used to return maximum value from result setMAX 

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Q:

Can’t update primary table’s primary key if row being modified has related rows in secondary table once referential integrity is enforced

A) TRUE B) FALSE
Answer & Explanation Answer: A) TRUE

Explanation:
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Q:

Breaking of relationships is allowed once referential integrity on a database is enforced

A) TRUE B) FALSE
Answer & Explanation Answer: B) FALSE

Explanation:

Breaking of relationships is prevented once referential integrity on a database is enforced

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