SQL Syntax

Question 1

SELECT

Answer 1

extracts data from a database

Question 2

UPDATE

Answer 2

updates data in a database

Question 3

DELETE

Answer 3

deletes data from a database

Question 4

INSERT INTO

Answer 4

inserts new data into a database

Question 5

CREATE DATABASE

Answer 5

creates a new database

Question 6

ALTER DATABASE

Answer 6

modifies a database

Question 7

CREATE TABLE

Answer 7

creates a new table

Question 8

ALTER TABLE

Answer 8

modifies a table

Question 9

DROP TABLE

Answer 9

deletes a table

Question 10

CREATE INDEX

Answer 10

creates an index (search key)

Question 11

DROP INDEX

Answer 11

deletes an index

Question 12

SELECT *

Answer 12

selects all the columns from the specific table

Question 13

SELECT DISTINCT

Answer 13

select all the different values from the specific columns in specific table,
a column often contains many duplicate values; and sometimes you only want to list the different (distinct) values. NOT LIST DUPLICATE

Question 14

SELECT COUNT

Answer 14

lists the number of different (distinct) countries in table ,,,doesNOT work for firefox, NOT supported for MS access databases.

Question 15

SELECT WHERE

Answer 15

is used to filter records. is used to extract only those records that fulfill a specified condition. USED in SELECT, UPDATE , DELETE statements.

Question 16

TEXT FIELDS VS NUMBERIC FIELDS

Answer 16

TEXT=require single quotes around text values(most database systems will also allow double quotes).
NUMERIC= should NOT be enclosed in quotes

Question 17

Operators in the WHERE Clause

Answer 17

=	Equal	
>	Greater than	
<	Less than	
>=	Greater than or equal	
<=	Less than or equal	
<>	Not equal. Note: In some versions of SQL this operator may be written as !=	

BETWEEN Between a certain range

LIKE Search for a pattern

IN To specify multiple possible values for a column

Question 18

The SQL AND , OR and NOT Operators

Answer 18

The WHERE clause can be combined with AND, OR, and NOT operators.

The AND and OR operators are used to filter records based on more than one condition:

The AND operator displays a record if all the conditions separated by AND are TRUE.
The OR operator displays a record if any of the conditions separated by OR is TRUE.
The NOT operator displays a record if the condition(s) is NOT TRUE.

Question 19

AND Syntad

Answer 19

SELECT column1, column2, …
FROM table_name
WHERE condition1 AND condition2 AND condition3 …;

all conditions must be true

Question 20

OR Syntax

Answer 20

SELECT column1, column2, …
FROM table_name
WHERE condition1 OR condition2 OR condition3 …;

atleast one condition must be true

Question 21

NOT Syntax

Answer 21

SELECT column1, column2, …
FROM table_name
WHERE NOT condition;

no condition must be true to display

Question 22

Combining AND, OR and NOT

Answer 22

You can also combine the AND, OR and NOT operators.

The following SQL statement selects all fields from “Customers” where country is “Germany” AND city must be “Berlin” OR “München” (use parenthesis to form complex expressions):

SELECT * FROM Customers
WHERE Country=’Germany’ AND (City=’Berlin’ OR City=’München’);

The following SQL statement selects all fields from “Customers” where country is NOT “Germany” and NOT “USA”:

Example
SELECT * FROM Customers
WHERE NOT Country=’Germany’ AND NOT Country=’USA’;

Question 23

SQL ORDER BY Keyword

Answer 23

The ORDER BY keyword is used to sort the result-set in ascending or descending order.

The ORDER BY keyword sorts the records in ascending order by default. To sort the records in descending order, use the DESC keyword.

SELECT column1, column2, …
FROM table_name
ORDER BY column1, column2, … ASC|DESC;

SEVERAL COLUMNS

SELECT * FROM Customers
ORDER BY Country, CustomerName;

ASC and DESC
SELECT * FROM Customers
ORDER BY Country ASC, CustomerName DESC;