PHP development basic tutorial AJAX and MySQL

AJAX database instance

AJAX can be used to communicate interactively with the database

The following The example will demonstrate how a web page reads information from the database via AJAX

Please select a customer in the drop-down list on the left:

This example consists of four elements:

• MySQL database

• Simple HTML form

• JavaScript

• PHP Page

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Database

This example requires the following data tables to be created in the database:

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##HTML form and JavaScript

See 1.php

     
     选择一个人： Peter Griffin 小 明 小 白   
 
 
选择相应用户，用户信息将在这里展示出来
  

## for the source code

#Source code explanation

After the user selects through the drop-down list, the showUser() function is executed through the onchange event

The showUser() function will perform the following steps:

Check if a user is selected
Create an XMLHttpRequest object
Create a function to be executed when the server response is ready
Send a request to a file on the server
Please note the parameter (q) added to the end of the URL (contains the contents of the drop-down list)

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##PHP page

The above The server page called via JavaScript is a PHP file named "2.php". The source code in

"2.php" will run a query against the MySQL database and then return the results in an HTML table:

  姓 名 年龄 家乡 工作  "; //循环显示出用信息 while($row = mysqli_fetch_array($result)){ echo ""; echo "".$row['FirstName'].""; echo "".$row['LastName'].""; echo "".$row['Age'].""; echo "".$row['Hometown'].""; echo "".$row['Job'].""; echo ""; } echo ""; ?>

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Learning experience

This example mainly includes the following knowledge points:

表 Form Basis: Pulling option

• ## On onchange Event: When the content of the domain changes,

• Series can be called, function transfer value

• # Ajax xmlhttprequest objects, when the server responds The function of executing, sending requests to the file on the server: See 1-5 Learning Experience

• # steal Dom GetelementByid () Method: Return to quoting the first object of the designated ID

• Create the database, connect to the database, select the database, set the character set, query from the database based on id, and loop out the contents of the database

• Functions related to the database:

mysqli_connect(): Open a new connection to the MySQL server

• mysqli_error(): Return to the previous A text error message generated by a MySQL operation.

• mysqli_select_db(): used to change the default database for the connection

• mysqli_query(): execute a query against the database

• mysqli_fetch_array(): Get a row from the result set as an associative array, a numeric array, or both