Category: PHP

SELECT / LIST Records From Database Table: PHP & MySQL

Video tutorial demonstrates selecting / listing / fetching of data / records from the database table and displaying it on the browser.

First look at these short videos:
Connect to the database
Simple / basic insertion operation
Insertion of Records into Database using Forms: PHP & MySQL (important)

SELECTING and Displaying Data
index.php

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< ?php
  include_once('db.php');
 
 $res = mysql_query("SELECT * FROM apple");
 
  while( $row = mysql_fetch_array($res) )
  echo "$row[id]. $row[name] <br />";
 
?>

Video Tutorial: SELECT / LIST Records From Database Table: PHP & MySQL


[youtube https://www.youtube.com/watch?v=OAT0iTXlqCk]

YouTube Link: https://www.youtube.com/watch?v=OAT0iTXlqCk [Watch the Video In Full Screen.]



Full code
index.php

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< ?php
include_once('db.php');
 
if(isset($_POST['name']))
{
  $name = $_POST['name'];
 
  if(mysql_query("INSERT INTO apple VALUES('','$name')"))
echo "Successful Insertion!";
  else
echo "Please try again";
}
 
 
$res = mysql_query("SELECT * FROM apple");
 
 
?>
 
<form action="." method="POST">
Name: <input type="text" name="name"/><br />
<input type="submit" value=" Enter "/>
</form>
 
<h1>List of companies ..</h1>
< ?php
while( $row = mysql_fetch_array($res) )
  echo "$row[id]. $row[name] <br />";
?>

while loop executes until there is data inside the table, once there is no more data to fetch, loop terminates.

MySQL Query

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mysql> SELECT * FROM apple;

This mysql statement fetches data from all the fields of the table.
We could specify fields and get only list of those values.

Ex:

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mysql> SELECT id FROM apple;

Using this we can get list of id’s only.

After fetching data from table apple

List of companies ..

1. Google
2. Apple
3. Microsoft
4. Oracle
5. Technotip

Insertion of Records into Database using Forms: PHP & MySQL

Video tutorial illustrates INSERTION of records into database using simple HTML form and minimal PHP scripting.

First look at these short videos:
Connect to the database
Simple / basic insertion operation

Form and PHP script, both in one file
index.php

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< ?php
include_once('db.php');
 
if($_POST['name'])
{
  $name = $_POST['name'];
 
  if(mysql_query("INSERT INTO apple VALUES('','$name')"))
echo "Successful Insertion!";
  else
echo "Please try again";
}
?>
 
<form action="." method="POST">
Name: <input type="text" name="name"/><br />
<input type="submit" value=" Enter "/>
</form>

. in action property of html form simply means that the user entered values will be passed on to itself.
Since we are using . in the action property, we are making use of user entered values in the same file by using if($_POST[‘name’]) PHP code.
we can even use if( isset($_POST[‘name’])) isset() is a PHP function to check whether a variable has some value or not.

Video Tutorial: Insertion of Records into Database using Forms: PHP & MySQL


[youtube https://www.youtube.com/watch?v=9BRiX3rXuRg]

YouTube Link: https://www.youtube.com/watch?v=9BRiX3rXuRg [Watch the Video In Full Screen.]



To know the differences between GET and POST methods:
GET Method In Action: Simple Form
POST Method In Action: Simple Form

Data in the database, as shown in the video:
1. Google
2. Apple
3. Microsoft
4. Oracle
5. Technotip

Insertion of Records into Database: PHP & MySQL

Video tutorial illustrates INSERTION of records into database via PHP script.

Simple / basic insertion operation:

First connect to the database.

Next, using simple MySQL query.
index.php

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< ?php
include_once('db.php');
 
 
if(mysql_query("INSERT INTO apple VALUES('','Oracle')"))
echo "Successful Insertion!";
else
echo "Please try again";
?>

make sure to watch other video about connecting to the database, to understand include_once(‘db.php’);

Video Tutorial: Insertion of Records into Database: PHP & MySQL


[youtube https://www.youtube.com/watch?v=GSLn77qbS1w]

YouTube Link: https://www.youtube.com/watch?v=GSLn77qbS1w [Watch the Video In Full Screen.]



die function:

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< ?php
 
   include_once('db.php');
 
   $res = mysql_query("INSERT INTO apple VALUES('','Oracle')") 
                            or die("sorry, database is busy!");
 
   echo "Successful insertion";
?>

if the insertion operation fails for some reason, the die function is invoked and the message “Sorry, database is busy!” is shown to the use and the script execution halts, and the “Successful insertion” message won’t be echoed.

Data in the database, as shown in the video:
1. Google
2. Apple
3. Microsoft
4. Oracle

Connecting To MySQL server From PHP

Most application programs need to be connected to the database inorder to do some basic operations like saving and retrieving the user details / data.

In this video tutorial we illustrate, how we need to connect to MySQL server from PHP script.

Connecting to MySQL server
db.php

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< ?php
$conn = mysql_connect('localhost','root','');
$db   = mysql_select_db('database_name', $conn);
?>

Include this file in all other files which needs to communicate with this database database_name

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< ?php
include_once('db.php');
?>
 
INSERT, SELECT, UPDATE, DELETE, DROP etc ..operations 
on the datbase.

Video Tutorial: Connecting To MySQL server From PHP


[youtube https://www.youtube.com/watch?v=EAJ0XsQysf8]

YouTube Link: https://www.youtube.com/watch?v=EAJ0XsQysf8 [Watch the Video In Full Screen.]



There are many variations of include:
include();
include_once();

require();
require_once();

require produces fatal error if the required file is not found. include produces warning when the file is not found.
include_once and require_once makes sure the files are included only once and not included multiple times in the same file.

Primary Foreign Unique Keys, AUTO_INCREMENT: MySQL

Video tutorial illustrates the use of Primary Key, Foreign Key, Unique Key, AUTO_INCREMENT and NOT NULL in MySQL.

Primary Key
The PRIMARY KEY constraint uniquely identifies each record in a database table.
Primary keys have unique values.
Primary Keys are NOT NULL by default.

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CREATE TABLE Apple
(
 id int NOT NULL,
 name varchar(255) NOT NULL,
 PRIMARY KEY(id)
);

Unique Key
The UNIQUE constraint uniquely identifies each record in a database table.

UNIQUE keys are not Primary Keys. but all Primary keys are Unique keys.

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CREATE TABLE Apple
(
 id int NOT NULL,
 name varchar(255) NOT NULL,
 UNIQUE(id)
);

Foreign Key
A FOREIGN KEY in one table points to a PRIMARY KEY in another table.

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CREATE TABLE Orders
(
 id int NOT NULL,
 O_No int NOT NULL,
 PRIMARY KEY(O_No),
 FOREIGN KEY(id) REFERENCES Apple(id)
);

If your MySQL uses InnoDB engine, then use the following query:

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CREATE TABLE Orders
(
 id int NOT NULL,
 O_No int NOT NULL,
 PRIMARY KEY(O_No),
 FOREIGN KEY(id) REFERENCES Apple(id)
)ENGINE=InnoDB;

Video Tutorial: Primary Foreign Unique Keys, AUTO_INCREMENT: MySQL


[youtube https://www.youtube.com/watch?v=01Y1T44D9JU]

YouTube Link: https://www.youtube.com/watch?v=01Y1T44D9JU [Watch the Video In Full Screen.]



phpMyAdmin UI Interface Options
Options for assigning Primary key, unique key to the attributes..also the edit and delete keys.

primary-unique-edit-delete

AUTO_INCREMENT and NOT NULL

auto-increment-not-null


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CREATE TABLE Apple
(
 id int NOT NULL AUTO_INCREMENT,
 name varchar(255) NOT NULL,
 PRIMARY KEY(id)
);

AUTO_INCREMENT is used for integer type data.. the advantage being, we need not explicitly send the data to this field. MySQL automatically inserts the value to this field.