How to Build a Dynamic WHERE Clause for a Multi-Parameter Search Form in PHP?

Search Form with Multiple Parameters

In a search form, allowing users to input multiple parameters can enhance the search functionality. However, this requires a modification of the search process.

Dynamic WHERE Clause

The key to enabling multiple parameters is to build the WHERE clause dynamically based on the user's input. Here's how to approach it in PHP using PDO:

$wheres = array();
$params = array();

if (!empty($_GET['id'])) {
    $wheres[] = 'a.uid = :uid';
    $params[':uid'] = $_GET['id'];
}
if (!empty($_GET['major'])) {
    $wheres[] = 'a.major = :major';
    $params[':major'] = $_GET['major'];
}
if (!empty($_GET['name'])) {
    $wheres[] = 'b.name LIKE :name';
    $params[':name'] = '%'.$_GET['name'].'%';
}

Here, we create an array $wheres to hold conditional statements and a $params array to store the corresponding parameter values. For each non-empty parameter, we add a condition to $wheres and store the parameter in $params.

Generating the SQL Query

We then concatenate the conditions from $wheres to form the WHERE clause:

if (!empty($wheres)) {
    $sql .= " WHERE " . implode(' AND ', $wheres);
}

The implode() function joins the conditions with the keyword 'AND'. We append this to the base SQL query.

Executing the Query and Displaying Results

Next, we prepare and execute the query:

$stmt = $db->prepare($sql);
$stmt->execute($params);

Finally, we iterate over the result set and display the desired student information, similar to the original code:

while ($student = $stmt->fetch()) {
    ...
}

This dynamic approach allows users to input multiple parameters, combining them to tailor their search results.

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