Why is it important to specify the columns in a SELECT query instead of using SELECT *?

Specifying the columns in a SELECT query is important because it allows you to retrieve only the necessary data from the database, improving query performance and reducing the amount of data transferred. Using SELECT * can result in fetching unnecessary columns, leading to increased network traffic and slower query execution. By explicitly listing the columns you need, you can also make your code more readable and maintainable. 

// Specify the columns in the SELECT query instead of using SELECT *
$query = "SELECT column1, column2, column3 FROM table_name";
$result = mysqli_query($connection, $query);

// Loop through the results
while($row = mysqli_fetch_assoc($result)) {
    // Access the specific columns by their names
    echo $row['column1'] . " - " . $row['column2'] . " - " . $row['column3'] . "<br>";
}

Keywords

PHP SELECT query columns performance optimization

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