What is the correct way to perform a JOIN in PHP when querying data from multiple tables?

When querying data from multiple tables in PHP, you can use the SQL JOIN clause to combine rows from two or more tables based on a related column between them. This allows you to retrieve data from multiple tables in a single query. To perform a JOIN in PHP, you need to construct the SQL query with the appropriate JOIN type (e.g., INNER JOIN, LEFT JOIN, RIGHT JOIN) and specify the columns to select from each table. 

<?php

// Establish a database connection
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

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

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// SQL query with JOIN
$sql = "SELECT table1.column1, table2.column2
        FROM table1
        INNER JOIN table2 ON table1.id = table2.id";

$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // Output data of each row
    while($row = $result->fetch_assoc()) {
        echo "Column1: " . $row["column1"]. " - Column2: " . $row["column2"]. "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();

?>

Keywords

PHP JOIN SQL database query

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