SQL for Database Construction Questions and Answers

Q: When a foreign key column is created without a corresponding foreign key constraint, we have created a "casual relationship" between the two tables.

Correct answer: TrueA casual relationship is one implied by the data but not declared to the DBMS: the foreign key column is present and the application relies on it, but no constraint enforces the reference. Nothing then prevents an orphaned value, and the integrity depends entirely on every program getting it right.

Q: The SQL command to create a table is:

Correct answer: CREATE TABLE.CREATE TABLE defines the table, its columns, their data types and null status, and the constraints on them. ALTER TABLE changes a table that already exists, and the other two are not SQL statements at all - a reminder that the data definition verbs are few and fixed: CREATE, ALTER and DROP.

Q: What is not an advantage of stored procedures?

Correct answer: Increased network trafficStored procedures reduce network traffic, since only the call and its parameters cross the network instead of the statements and their intermediate results. The other three are genuine advantages: permissions can be granted on the procedure rather than the tables, the plan is compiled and reused, and the code is written once and shared.

Q: A SQL view is a virtual table that is constructed from other tables or views.

Correct answer: TrueA view is virtual because nothing is stored but its defining query; the rows are produced each time it is read. It may be built from tables or from other views, which allows layers of abstraction, and it behaves like a table in a query while carrying none of a table’s storage.

Q: There are three SQL data modification operations: insert, modify and delete.

Correct answer: TrueINSERT, UPDATE and DELETE are the three data manipulation operations that change stored data, and every modification a program makes is one of them. They are distinct from the data definition statements, which change structure rather than content.

Q: The SQL MAKE TABLE command is used to construct tables, define columns, define column constraints and create relationships.

Correct answer: FalseThere is no MAKE TABLE statement in SQL. The verb is CREATE TABLE, and it does everything the statement describes - defines columns and their constraints and, through foreign key declarations, the relationships between tables.

Q: A stored procedure is a program that performs some common action on database data and is stored in the database.

Correct answer: TrueThat is the definition, and the two halves are both essential: the procedure performs an action on the data, and it lives in the database rather than in the application. From that follow its advantages - one copy to maintain, a compiled plan to reuse, permissions granted on the procedure, and little traffic across the network.

Q: What is an SQL virtual table that is constructed from other tables?

Correct answer: A viewA view is virtual: nothing is stored but the SELECT that defines it, and the rows are produced when it is queried. That is what makes it always current and what distinguishes it from a table, which holds data, and from query results, which are a one-off answer rather than a named object.

Q: The SQL DELETE statement is used to delete both the table structure and table data.

Correct answer: FalseDELETE removes rows and leaves the table, its definition, its indexes and its constraints in place; an empty table remains. Removing the structure as well is DROP TABLE. The distinction is worth being certain of, since the two mistakes are not equally recoverable.

Q: Which of the following is an SQL trigger supported by Oracle?

Correct answer: All of the above.Oracle supports BEFORE, AFTER and INSTEAD OF triggers. The BEFORE trigger is the one that distinguishes it from SQL Server, which has only the other two, and it is convenient for validating or altering values before they are written.

21.

When a foreign key column is created without a corresponding foreign key constraint, we have created a "casual relationship" between the two tables.

A.True
B.False

Answer: A

Correct answer: True

A casual relationship is one implied by the data but not declared to the DBMS: the foreign key column is present and the application relies on it, but no constraint enforces the reference. Nothing then prevents an orphaned value, and the integrity depends entirely on every program getting it right.

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22.

The SQL command to create a table is:

A.MAKE TABLE.
B.ALTER TABLE.
C.DEFINE TABLE.
D.CREATE TABLE.

Answer: D

Correct answer: CREATE TABLE.

CREATE TABLE defines the table, its columns, their data types and null status, and the constraints on them. ALTER TABLE changes a table that already exists, and the other two are not SQL statements at all - a reminder that the data definition verbs are few and fixed: CREATE, ALTER and DROP.

Discuss in Forum

23.

What is not an advantage of stored procedures?

A.Greater security
B.SQL can be optimized
C.Code sharing
D.Increased network traffic

Answer: D

Correct answer: Increased network traffic

Stored procedures reduce network traffic, since only the call and its parameters cross the network instead of the statements and their intermediate results. The other three are genuine advantages: permissions can be granted on the procedure rather than the tables, the plan is compiled and reused, and the code is written once and shared.

Discuss in Forum

24.

A SQL view is a virtual table that is constructed from other tables or views.

A.True
B.False

Answer: A

Correct answer: True

A view is virtual because nothing is stored but its defining query; the rows are produced each time it is read. It may be built from tables or from other views, which allows layers of abstraction, and it behaves like a table in a query while carrying none of a table’s storage.

Discuss in Forum

25.

There are three SQL data modification operations: insert, modify and delete.

A.True
B.False

Answer: A

Correct answer: True

INSERT, UPDATE and DELETE are the three data manipulation operations that change stored data, and every modification a program makes is one of them. They are distinct from the data definition statements, which change structure rather than content.

Discuss in Forum

26.

The SQL MAKE TABLE command is used to construct tables, define columns, define column constraints and create relationships.

A.True
B.False

Answer: B

Correct answer: False

There is no MAKE TABLE statement in SQL. The verb is CREATE TABLE, and it does everything the statement describes - defines columns and their constraints and, through foreign key declarations, the relationships between tables.

Discuss in Forum

27.

A stored procedure is a program that performs some common action on database data and is stored in the database.

A.True
B.False

Answer: A

Correct answer: True

That is the definition, and the two halves are both essential: the procedure performs an action on the data, and it lives in the database rather than in the application. From that follow its advantages - one copy to maintain, a compiled plan to reuse, permissions granted on the procedure, and little traffic across the network.

Discuss in Forum

28.

What is an SQL virtual table that is constructed from other tables?

A.Just another table
B.A view
C.A relation
D.Query results

Answer: B

Correct answer: A view

A view is virtual: nothing is stored but the SELECT that defines it, and the rows are produced when it is queried. That is what makes it always current and what distinguishes it from a table, which holds data, and from query results, which are a one-off answer rather than a named object.

Discuss in Forum

29.

The SQL DELETE statement is used to delete both the table structure and table data.

A.True
B.False

Answer: B

Correct answer: False

DELETE removes rows and leaves the table, its definition, its indexes and its constraints in place; an empty table remains. Removing the structure as well is DROP TABLE. The distinction is worth being certain of, since the two mistakes are not equally recoverable.

Discuss in Forum

30.

Which of the following is an SQL trigger supported by Oracle?

A.BEFORE
B.INSTEAD OF
C.AFTER
D.All of the above.

Answer: D

Correct answer: All of the above.

Oracle supports BEFORE, AFTER and INSTEAD OF triggers. The BEFORE trigger is the one that distinguishes it from SQL Server, which has only the other two, and it is convenient for validating or altering values before they are written.

Discuss in Forum

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