(6) Fundamentals of SQL

Question 1

Alias

Answer 1

An alternative name for a column or a table in a SQL statement.

Question 2

ALTER TABLE

Answer 2

The SQL command used to make changes to table structure. When the command is followed by a keyword (ADD or MODIFY), it adds a column or changes column characteristics.

Question 3

AND

Answer 3

The SQL logical operator used to link multiple conditions expressions in a WHERE or HAVING clause. It requires that all conditional expressions evaluate to true.

Question 4

AVG

Answer 4

A SQL aggregate fusion that outputs the mean average for a specified column or expression.

Question 5

BETWEEN

Answer 5

In SQL, a special comparison operator used to check whether a value is within a range of specified values.

Question 6

Boolean algebra

Answer 6

A branch of mathematics that uses logical operators OR, AND, and NOT.

Question 7

Cascading order sequence

Answer 7

A nested ordering for a set of rows, such as a list in which all last names are alphabetically ordered and, within the last names, all first names are ordered.

Question 8

COMMIT

Answer 8

The SQL command that permanently writes data changes to a database.

Question 9

COUNT

Answer 9

A SQL aggregate function that outputs the number of rows containing not null values for a given column or expression, sometimes used in conjunction with the DISTINCT clause.

Question 10

CREATE INDEX

Answer 10

A SQL command that creates indexes on the basis of a selected attribute or attributes.

Question 11

CREATE TABLE

Answer 11

A SQL command that creates a table’s structures using the characteristics and attributes given.

Question 12

DELETE

Answer 12

A SQL command that allows data rows to be deleted from a table.

Question 13

DISTINCT

Answer 13

A SQL clause that produces only a list of values that are different from one another.

Question 14

DROP INDEX

Answer 14

A SQL command used to delete database objects such as table’s, views, indexes, and users.

Question 15

DROP TABLE

Answer 15

A SQL command used to delete database objects such as table’s, views, indexes, and users.

Question 16

EXISTS

Answer 16

In SQL, a comparison operator that checks whether a sub query returns any rows.

Question 17

FROM

Answer 17

A SQL clause that specifies the table or table’s from which data is to be retrieved.

Question 18

GROUP BY

Answer 18

A SQL clause used to create frequency distributions when combined with any of the aggregate functions in a SELECT statement.

Question 19

HAVING

Answer 19

A clause applied to the output of a GROUP BY operation to restrict selected rows.

Question 20

IN

Answer 20

In SQL, a comparison operator used to check whether a value is among a list of specified values.

Question 21

inner query

Answer 21

A query that is embedded or nested inside another query.

Question 22

INSERT

Answer 22

A SQL command that allows the insertion of one or more data rows into a table.

Question 23

International Organization for Standardization (ISO)

Answer 23

An organization formed to develop standards for diverse network systems.

Question 24

IS NULL

Answer 24

In SQL, a comparison operator used to check whether an attribute has a value.

Question 25

LIKE

Answer 25

In SQL, a comparison used to check whether an attribute's text value matches a specified string pattern.

Question 26

MAX

Answer 26

A SQL aggregate function that yields the maximum attribute in a given column.

Question 27

MIN

Answer 27

A SQL aggregate function that yields the minimum attribute in a given column.

Question 28

Nested query

Answer 28

In SQL, a query that is embedded in another query.

Question 29

NOT

Answer 29

A SQL logical operator that negates a given predicate.

Question 30

OR

Answer 30

the SQL logical operator used to link multiple conditional expressions in a WHERE or HAVING clause. It requires only one of the conditional expressions to be true.

Question 31

ORDER BY

Answer 31

A SQL clause that is useful for ordering the output of a SELECT query (for example, in ascending or descending order).

Question 32

ROLLBACK

Answer 32

A SQL command that restores the database table contents to the condition that existed after the last COMMIT statement.

Question 33

Rules of precedence

Answer 33

Basic algebra is rules that specify the order in which operations are performed. For example, operations within parentheses are executed first, so in the equation 2 + (3 5), the multiplication is calculated first, making the correct answer 17.

Question 34

Subquery

Answer 34

A query that is embedded (or nested) inside another query.

Question 35

SUM

Answer 35

A SQL aggregate function that yields the sum of all values for a given column or expression.

Question 36

UPDATE

Answer 36

A SQL command that allows attribute values to be changed in one or more rows of a table.

Question 37

WHERE

Answer 37

A SQL clause that adds conditional restrictions to a SELECT statement that limit the rows returned by the query.

Question 38

Wildcard character

Answer 38

A symbol that can be used as a general substitute for: (1) all columns in a table (*) when used in an attribute list of a SELECT statement or, (2) zero or more characters in a SQL LIKE clause condition (% and _ ).