How can one efficiently use WHERE clauses in SQL queries to filter results in PHP?

When writing SQL queries in PHP, WHERE clauses can be used to filter results based on specific conditions. To efficiently use WHERE clauses, it's important to carefully construct the conditions to accurately retrieve the desired data. This can involve using logical operators like AND and OR, as well as comparison operators such as =, <, >, etc. By properly utilizing WHERE clauses, you can effectively narrow down the results returned by your SQL queries. 

&lt;?php
// Establish a database connection
$servername = &quot;localhost&quot;;
$username = &quot;username&quot;;
$password = &quot;password&quot;;
$dbname = &quot;database&quot;;

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn-&gt;connect_error) {
    die(&quot;Connection failed: &quot; . $conn-&gt;connect_error);
}

// SQL query with WHERE clause to filter results
$sql = &quot;SELECT * FROM table_name WHERE column_name = &#039;desired_value&#039;&quot;;

$result = $conn-&gt;query($sql);

if ($result-&gt;num_rows &gt; 0) {
    // Output data of each row
    while($row = $result-&gt;fetch_assoc()) {
        echo &quot;Column Name: &quot; . $row[&quot;column_name&quot;]. &quot;&lt;br&gt;&quot;;
    }
} else {
    echo &quot;0 results&quot;;
}

$conn-&gt;close();
?&gt;

Keywords

PHP SQL queries WHERE clauses filter results efficiency

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