In how many ways we can retrieve the data in the result set of MySQL using PHP?

You can do it by 4 Ways
1. mysql_fetch_row.
2. mysql_fetch_array
3. mysql_fetch_object
4. mysql_fetch_assoc

Why use views. View rules and restrictions.

Views use:

• Same table can be created in different forms
• Can hide certain columns of a table
• Can save time and efforts for queries that are frequently executed
• Can help in manipulating data

Rules and restriction:

• The SELECT statement cannot contain a subquery in the FROM clause.
• The SELECT statement cannot refer to system or user variables.
• Any table or view referred to in the definition must exist
• A temporary view cannot be created
• Any tables named in the view definition must exist at definition time
• A trigger cannot be associated with a view

CREATE VIEW Syntax with an example

SQL CREATE VIEW: A view is a virtual table. A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.
Syntax:
CREATE VIEW view_name AS
SELECT column_name(s)
FROM table_name
WHERE condition
Example:
CREATE VIEW [sample] AS
SELECT employeeID,employeeName
FROM employee
WHERE salary > 10000

ALTER VIEW Syntax with an example

The existing view can be updated as shown below. Below we are adding an additional columns salary.
CREATE VIEW [employee_details] AS
SELECT employeeID,employeename,salary
FROM Employee
WHERE Discontinued=No

DROP VIEW Syntax with an example

The view can be dropped by using the DROP statement.
Syntax:

DROP view view_name

Explain how to use ORDER BY clause inside PHP Script.

ORDER BY clause in PHP is used to sort the data in the result set. It sorts data in ascending manner by default. To sort data in descending order, DESC is used.
Example:

<?php
//connect to database
mysql_select_db("my_db", $con);
//Query to list employees ordered by AGE
$result = mysql_query("SELECT * FROM Employee ORDER BY age");
?>

Explain SELECT Statement by providing examples for the following.

• Retrieving Individual Columns
• Retrieving multiple Columns
• Retrieving ALL Columns
• Retrieving Distinct Rows

Select statement allows selecting and retrieving data from tables.
Syntax:
Select * | column_name from table name

Retrieving Individual Columns
Select employee_name from employee Where emp_id > 1

Retrieving multiple Columns
Select employee_firstname, employee_lastname from employee Where emp_id > 1

Retrieving ALL Columns
Select * from employee Where emp_id > 1


Retrieving Distinct Rows
Select disctint mobile_number From employee

Explain the use of Group By with an example.

Group By is used along with aggregate functions to group the result-set by one or more columns.

Example: The query below will display employees along with their salaries.


SELECT employee_name,SUM(salary) FROM employee GROUP BY employee_name