SELECT DECK 1

Question 1

What is the shorthand form of the DESCRIBE command?

Answer 1

DESC

Question 2

What is the name of the generic all-purpose table belonging to the SYS schema?

Answer 2

DUAL

Question 3

Do blank spaces count as NULL?

Answer 3

No. NULL is only an absence of data.

Question 4

What three relational concepts are present in the SELECT statement?

Answer 4

PROJECT, SELECTION, and JOINING.

Question 5

PROJECTION refers to what?

Answer 5

PROJECTION refers to the restriction of columns selected from a table.

Question 6

SELECTION refers to what?

Answer 6

SELECTION refers to the restriction of rows selected from a table.

Question 7

The relational concept JOIN refers to what?

Answer 7

JOIN refers to the interaction of tables with each other in a query.

Question 8

What are the two mandatory clauses in an SQL query?

Answer 8

The SELECT clause and the FROM clause.

Question 9

What is an ALIAS?

Answer 9

An alternate name for referencing a column or expression.

Question 10

How do you eliminate duplicate results from a query?

Answer 10

Include the DISTINCT keyword.

Question 11

In what clause is the DISTINCT keyword used?

Answer 11

In the SELECT clause.

Question 12

In Oracle, how do you specify which terms are affected by DISTINCT?

Answer 12

DISTINCT refers to the values listed after it and before the FROM clause.

Question 13

What operations may be used on DATE or TIMESTAMP values?

Answer 13

Addition and subtraction only.

Question 14

The process of modeling data into relational tables is known as…?

Answer 14

Normalization.

Question 15

In Normalization, what is the First Normal Form?

Answer 15

Removal of repeating groups

Question 16

In Normalization, what is the Second Normal Form?

Answer 16

Removal of columns that are not dependent on the primary key.

Question 17

In Normalization, what is the Third Normal Form?

Answer 17

Removal of all columns that are interdependent.

Question 18

In standard notation for text description of a table, what symbol is used for primary key columns?

Answer 18

A hash symbol (#)

Question 19

In standard notation for text description of a table, what symbol is used for foreign key columns?

Answer 19

A backslash ()

Question 20

In standard notation for text description of a table, what symbol is used for mandatory (NOT NULL) columns?

Answer 20

An asterisk (*)

Question 21

In standard notation for text description of a table, what symbol is used for optional columns?

Answer 21

A lower-case letter “O” (o)

Question 22

How many Normal Forms exist for Normalization?

Answer 22

At least five, but only the first three are normally used.

Question 23

What is an Entity-Relationship diagram?

Answer 23

A graphical representation of the connections between tables.

Question 24

Are SQL commands case-sensitive?

Answer 24

No.

Question 25

Is a statement terminator required?

Answer 25

Not always, but it's a good idea to include one anyway.

Question 26

What is the definition of a primary key?

Answer 26

It's an attribute (or attributes) that uniquely identify a record.

Question 27

What is the definition of a foreign key?

Answer 27

It's a column (or concat of several columns) that uniquely identify a related row in another rtable.

Question 28

A foreign key in one table will match . . . in another table.

Answer 28

a primary key

Question 29

The basis of the many-to-one relationship is . . .

Answer 29

the foreign key.

Question 30

How is an ALIAS created?

Answer 30

Either list it immediately after the referenced column, or use the AS keyword.

Question 31

What format is returned for an unquoted alias?

Answer 31

Unquoted aliases are upper case.

Question 32

To specify case or use spaces in an ALIAS, you must . . .

Answer 32

surround the alias with double quotes.

Question 33

What is the concat operator?

Answer 33

The double-pipe ( || ).

Question 34

How do you specify a char literal?

Answer 34

With single quote marks.

Question 35

When are single quote marks used?

Answer 35

To specify a char literal.

Question 36

How do you specify a single quote in a literal string?

Answer 36

Use a double quote, as in 'That is Dippy''s calculator'

Question 37

What is a literal quote?

Answer 37

a lower-case q, followed by a single quote, followed by the char you want to use to indicate a quote mark, as in SELECT q'X

Question 38

Do any rational people use literal quotes?

Answer 38

Of course not. But you might run into them sometime, so you should know what they are.

Question 39

NULL refers to . . .

Answer 39

an absence of data.

Question 40

Any arithmetic calculation with a NULL value returns . . .

Answer 40

NULL.

Question 41

Division by zero results in an error. Division by NULL results in

Answer 41

NULL.

Question 42

When a NULL value is encountered by the concat operator . . .

Answer 42

it is ignored.

Question 43

The WHERE clause in a SELECT statement is sometimes referred to as . . .

Answer 43

the predicate.