PHP - AJAX and MySQL
PHP - AJAX and MySQL
AJAX can be used to communicate interactively with the database.
AJAX Database Example
The following example will demonstrate how a web page reads information from the database through AJAX:
Example
Explanation of examples - MySQL database
In the above example, the database table we use is as follows:
Explanation of examples - HTML page
When the user selects a user in the drop-down list above, the name "showUser()" will be executed " The function. This function is triggered by the "onchange" event:
<html> <head> <script> function showUser(str) { if (str=="") { document.getElementById("txtHint").innerHTML=""; return; } if (window.XMLHttpRequest) { // IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码 xmlhttp=new XMLHttpRequest(); } else { // IE6, IE5 浏览器执行代码 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { document.getElementById("txtHint").innerHTML=xmlhttp.responseText; } } xmlhttp.open("GET","getuser.php?q="+str,true); xmlhttp.send(); } </script> </head> <body> <form> <select name="users" onchange="showUser(this.value)"> <option value="">Select a person:</option> <option value="1">Peter Griffin</option> <option value="2">Lois Griffin</option> <option value="3">Glenn Quagmire</option> <option value="4">Joseph Swanson</option> </select> </form> <br> <div id="txtHint"><b>Person info will be listed here.</b></div> </body> </html>
showUser() function will perform the following steps:
·
· Create a function that executes when the server response is ready Content)
PHP fileThe server page called above through JavaScript is a PHP file named "getuser.php".
The source code in "getuser.php" runs a query against the MySQL database and returns the results in an HTML table: <?php
$q=$_GET["q"];
$con = mysqli_connect('localhost','peter','abc123','my_db');
if (!$con)
{
die('Could not connect: ' . mysqli_error($con));
}
mysqli_select_db($con,"ajax_demo");
$sql="SELECT * FROM user WHERE id = '".$q."'";
$result = mysqli_query($con,$sql);
echo "<table border='1'>
<tr>
<th>Firstname</th>
<th>Lastname</th
<th>Age</th>
<th>Hometown</th>
<th>Job</th>
</tr>";
while($row = mysqli_fetch_array($result))
{
echo "<tr>";
echo "<td>" . $row['FirstName'] . "</td>";
echo "<td>" . $row['LastName'] . "</td>";
echo "<td>" . $row['Age'] . "</td>";
echo "<td>" . $row['Hometown'] . "</td>";
echo "<td>" . $row['Job'] . "</td>";
echo "</tr>";
}
echo "</table>";
mysqli_close($con);
?>
Explanation: When the query is sent from JavaScript to the PHP file , will happen:
1. PHP opens a connection to the MySQL database
2. Find the selected user
Create an HTML table, fill in the data, and send back "txtHint " Placeholder