SQL

Question 1

Structured Query Language

Answer 1

Simple programming language with less than 100 words syntax which is used to manipulate data stored in a database. It gets its name from the specific order in which queries and subqueries are given and executed.

Question 2

INSERT

Answer 2

Adding table rows. Can violate key constraints, including:
Primary key entered that already exists
Primary key is null
Foreign key entered that does not correspond to a primary key in another table

Question 3

COMMIT

Answer 3

Saving table changes

Question 4

SELECT

Answer 4

Listing table rows

Question 5

UPDATE

Answer 5

Updating table rows, modify data in table using UPDATE SET WHERE
Changes specific data within a table/database (cr: ALTER)

Question 6

ROLLBACK

Answer 6

Restoring table contents to state prior to changes (since last COMMIT)

Question 7

DELETE

Answer 7

Deleting table rows

Question 8

INSERT + SELECT

Answer 8

Inserting table rows with a select subquery, copying rows from one table into another

Question 9

NULL

Answer 9

Used with INSERT when a cell value is missing

Question 10

FROM

Answer 10

applies query to specific table within database

Question 11

WHERE

Answer 11

used to apply conditional restrictions

Question 12

=

Answer 12

equal to

Question 13

>

Answer 13

greater than

Answer 14

less than

Question 15

> =

Answer 15

greater than or equal to

Question 16

<=

Answer 16

less than or equal to

Question 17

<> or !=

Answer 17

not equal to

Question 18

SELECT
FROM
WHERE

Answer 18

Select with: equality comparisons, not equal to, restriction, comparison on characters, date comparison, statement with a computed column, statement with computed column and an alias,

Question 19

Arithmetic Operators: The Rule of Precedence(which operator goes first ?)‏

Answer 19

Perform operations within parentheses
Perform power operations
Perform multiplications and divisions
Perform additions and subtractions

Question 20

OR/AND/NOT

Answer 20

Logical operator. Used in conditional expressions

Question 21

BETWEEN

Answer 21

special operator. checks whether an attribute value is within a range

Question 22

IS NULL

Answer 22

special operator. checks whether an attribute value is null

Question 23

LIKE

Answer 23

special operator. checks whether an attribute value matches a given string pattern

Question 24

IN

Answer 24

special operator. checks whether an attribute value matches any given value within a list

Question 25

EXISTS

Answer 25

special operator. checks whether a subquery returns any rows

Question 26

data definition language

Answer 26

used to create new tables
does not deal with data
in some DBMSs SQL is not needed to create tables

Question 27

GROUP BY

Answer 27

Groups the selected rows based on one or more attributes.

Question 28

HAVING

Answer 28

Restricts the selection of grouped rows based on a condition

Question 29

ORDER BY

Answer 29

Orders the selected rows based on one or more attributes

Question 30

DISTINCT

Answer 30

limits values to unique values

Question 31

COUNT

Answer 31

Aggregate function. Returns the number of rows with non-null values for a given column.

Question 32

MIN

Answer 32

Aggregate function. Returns the minimum attribute value found in a given column

Question 33

MAX

Answer 33

Aggregate function. Returns the maximum attribute value found in a given column

Question 34

SUM

Answer 34

Aggregate function. Returns the sum of all values for a given column

Question 35

AVG

Answer 35

Aggregate function. Returns the average of all the values forgiven column

Question 36

CREATE SCHEMA AUTHORISATION

Answer 36

Create a database schema

Question 37

CREATE TABLE

Answer 37

Creates a new table in the user’s database schema

Question 38

NOT NULL

Answer 38

Ensures that a column will not have null values

Question 39

UNIQUE

Answer 39

Ensures that a column will not have duplicate values

Question 40

PRIMARY KEY

Answer 40

Defines a primary key for a table

Question 41

FOREIGN KEY

Answer 41

Defines a foreign key for a table

Question 42

DEFAULT

Answer 42

Defines a default value for a column (when no value is given)

Question 43

CHECK

Answer 43

Validate the data in an attribute

Question 44

CREATE INDEX

Answer 44

Create an index for a table

Question 45

CREATE VIEW

Answer 45

Create a dynamic subset of rows and columns from one or more tables

Question 46

ALTER TABLE

Answer 46

Modifies a table’s definition (ads modifies or delete attributes or constraints)
changes general structure of data (cr: UPDATE)

Question 47

CREATE TABLE AS

Answer 47

Create a new table based on a query in the user’s database schema

Question 48

DROP TABLE

Answer 48

Permanently deletes a table (and it’s data)

Question 49

DROP INDEX

Answer 49

Permanently deletes an index

Question 50

DROP VIEW

Answer 50

Permanently deletes a view

Question 51

order #1

Answer 51

INSERT
COMMIT
SELECT 
UPDATE
ROLLBACK
DELETE
INSERT + SELECT

Question 52

use brackets if you want

Answer 52

values checked in a specific order otherwise it’ll be done left to right

Question 53

if you need to check the same info in different tables (e.g. customer codes) use

Answer 53

T1.CUS_CODE = T2.CUS_CODE structure

Question 54

when copying parts of a table

Answer 54

create new part table then use INSERT INTO command

Question 55

order #2

Answer 55

SELECT 
FROM 
WHERE 
GROUP BY 
HAVING 
ORDER BY

Question 56

when you want information from multiple tables

Answer 56

you must use a join operator