PHP112

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Main Page >> Web Application Development >> Workbook >> Simple HTML/PHP/MySQL example

A Simple HTML/PHP/MySQL Example

The following example will:

  1. use a form to gather criteria for a search
  2. pass the criteria to a PHP script
  3. build a custom query
  4. execute the query against a database, returning results
  5. output the results

See working example here.

1. A form to gather criteria (pets-form.html)

<html>
  <head>
   <title>Part 1 - Form</title>
  </head>
  <body>
   <form action="pets-search.php" method="post">
    <p>
     Enter pet's name: <input type="text" name="searchName">
    </p>
    <p>
     <input type="submit" value="Search">
    </p>
   </form>
  </body>
</html>

2. The PHP script (pets-search.php)

<?php

// Connect to server/database
$mysqli = mysqli_connect("localhost", "YOUR USERNAME", "YOUR PASSWORD", "YOUR DB");
if (mysqli_connect_errno($mysqli)) {
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

// Build custom SQL query
$sql = "SELECT name, species, age FROM pet";

// Add search criteria, if provided
if($_POST['searchName'] != "")
  $sql.= " WHERE name LIKE '%" . $_POST['searchName'] . "%'";
  
// Run SQL query
$res = mysqli_query($mysqli, $sql);

// How many rows were returned?
$num_pets = mysqli_num_rows($res);

if($num_pets == 0)
  print("<p>No pet with that name, sorry...</p>");
else {
  print("<p>We found $num_pets pet(s) matching thay name...</p>");
  
  // Loop through resultset and display each field's value
  while($row = mysqli_fetch_assoc($res)) {
    echo $row['name']. " - ". $row['species'] ."<br>";
  }
}

?>

Deconstruction of the example

pets-form.html

This line in very important:

<form action="pets-search.php" method="post">

It specifies that anything entered in the current form should be posted to a file called pets-search.php. Obviously the latter should match the name of YOUR file.

On this line of code:

Enter pet's name: <input type="text" name="searchName">

It is important to note the name of the text field ("searchName"), as we will need it in the script below.

pets-search.php

A lot of the code above is similar to the previous section, so let's focus on what's new:

// Build custom SQL query
$sql = "SELECT name, species, age FROM pet";

// Add search criteria, if provided
if($_POST['searchName'] != "")
  $sql.= " WHERE name LIKE '%" . $_POST['searchName'] . "%'";

The code above is very important, so please make sure you understand is fully.

First, we define our basic SQL query, as per previous example.

$sql = "SELECT name, species, age FROM pet";

Then, we check if a value was typed in the form, and more specifically in the "searchName" field. We do this by accessing the $_POST superglobal, which contains all values POSTED to the current script.

if($_POST['searchName'] != "")

So if the user type "Bob" in the text field on the form, $_POST['searchName'] will contain the value "Bob".

If a value WAS typed (i.e. the field is not blank), we add the following WHERE clause to our basic query:

  $sql.= " WHERE name LIKE '%" . $_POST['searchName'] . "%'";

Which equates to adding:

WHERE name LIKE '%Bob%'

(assuming the user typed "Bob" in the form). This will perform a partial search on the value provided. More on the SQL LIKE operator here.

// How many rows were returned?
$num_pets = mysqli_num_rows($res);

if($num_pets == 0)
  print("<p>No pet with that name, sorry...</p>");
else {
  print("<p>We found $num_pets pet(s) matching thay name...</p>");

Then we check if the search returned anything, by checking the number of rows in the result-set. And display a different message accordingly.

Everything else is pretty much the same as before.

Try it

  • Implement and test the code above
  • Modify the code above so that it searches on the species rather than the name
  • Modify the code above so that it searches on both species and name

Ready to move on?

Let's tackle this week's mini-task!