How can PHP developers optimize code readability and performance by utilizing functions like mysql_num_rows() and LEFT JOIN in SQL queries?

To optimize code readability and performance in PHP, developers can utilize functions like mysql_num_rows() to efficiently retrieve the number of rows in a result set, and LEFT JOIN in SQL queries to combine data from two or more tables based on a related column. This helps in reducing the number of queries executed and improves the overall efficiency of the code. 

// Example code snippet using mysql_num_rows() and LEFT JOIN in SQL query

// Connect to the database
$conn = mysqli_connect("localhost", "username", "password", "database");

// Perform a LEFT JOIN query to retrieve data from two tables
$query = "SELECT table1.column1, table2.column2
          FROM table1
          LEFT JOIN table2 ON table1.id = table2.id";

$result = mysqli_query($conn, $query);

// Check the number of rows in the result set
$num_rows = mysqli_num_rows($result);

// Display the data retrieved from the query
if ($num_rows > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "Column 1: " . $row['column1'] . ", Column 2: " . $row['column2'] . "<br>";
    }
} else {
    echo "No results found.";
}

// Close the database connection
mysqli_close($conn);

Keywords

PHP mysql_num_rows() LEFT JOIN code readability performance

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