PHP with MYSQL Database connection


Create a Connection to a MySQL Database

Before you can access data in a database, you must create a connection to the database.
In PHP, this is done with the mysql_connect() function.

Syntax

mysql_connect(servername,username,password); 
Example
<?php
$con = mysql_connect("localhost","root","");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

?> 

Create a Database

The CREATE DATABASE statement is used to create a database in MySQL.

Syntax

CREATE DATABASE database_name 
Example:
<?php
$con = mysql_connect("localhost","root","");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

if (mysql_query("CREATE DATABASE my_db",$con))
  {
  echo "Database created";
  }
else
  {
  echo "Error creating database: " . mysql_error();
  }

mysql_close($con);
?>  
CREATE TABLE
$sql = "CREATE TABLE Persons
(
  id intNOT NULL AUTO_INCREMENT ,
FirstName varchar(15),
LastName varchar(15),
Age int
)";
Using PRIMARY KEY :
$sql = "CREATE TABLE Persons
(
  id int NOT NULL AUTO_INCREMENT,
PRIMARY KEY(personID),
FirstName varchar(15),
LastName varchar(15),
Age int
)";





INSERT QUERY

SYNTAX:
INSERT INTO table_name (column1, column2, column3,...)
VALUES (value1, value2, value3,...)  

 Example:
<?php
$con = mysql_connect("localhost","root","");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("my_db", $con);

mysql_query("INSERT INTO Persons (FirstName, LastName, Age)
VALUES ('Peter', 'Griffin',35)");

mysql_query("INSERT INTO Persons (FirstName, LastName, Age)
VALUES ('Glenn', 'Quagmire',33)");

mysql_close($con);
?>  

Insert Data From a Form Into a Database

Now we will create an HTML form that can be used to add new records to the "Persons" table.
Here is the HTML form:
<html>
<body>

<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname">
Lastname: <input type="text" name="lastname">
Age: <input type="text" name="age">
<input type="submit">
</form>

</body>
</html>
When a user clicks the submit button in the HTML form in the example above, the form data is sent to "insert.php".
The "insert.php" file connects to a database, and retrieves the values from the form with the PHP $_POST variables.
Then, the mysql_query() function executes the INSERT INTO statement, and a new record will be added to the "Persons" table.
Here is the "insert.php" page:

<?php
$con = mysql_connect("localhost","root","");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("my_db", $con);

$sql="INSERT INTO Persons (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";

if (!mysql_query($sql,$con))
  {
  die('Error: ' . mysql_error());
  }
echo "1 record added";

mysql_close($con);
?>

Select Data From a Database Table

The SELECT statement is used to select data from a database.

Syntax

SELECT column_name(s)
FROM table_name.
To get PHP to execute the statement above we must use the mysql_query() function. This function is used to send a query or command to a MySQL connection.

Example

The following example selects all the data stored in the "Persons" table (The * character selects all the data in the table):
<?php
$con = mysql_connect("localhost","root","");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

mysql_select_db("my_db", $con);

$result = mysql_query("SELECT * FROM Persons");

while($row = mysql_fetch_array($result))
  {
  echo $row['FirstName'] . " " . $row['LastName'];
  echo "<br />";
  }

mysql_close($con);
?>
The example above stores the data returned by the mysql_query() function in the $result variable.
Next, we use the mysql_fetch_array() function to return the first row from the recordset as an array. Each call to mysql_fetch_array() returns the next row in the recordset. The while loop loops through all the records in the recordset. To print the value of each row, we use the PHP $row variable ($row['FirstName'] and $row['LastName']).
The output of the code above will be:
Rahul Sharma
Aman Singh


Sync between two tables
--------------------------------
INSERT INTO <totable> SELECT * FROM <from table>

Copy data from one table to other

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