In what situations would using a "select count" query be more efficient than a "select * where" query in PHP when checking for existing data?

Using a "select count" query would be more efficient than a "select * where" query when checking for existing data because it only returns the count of rows that match the specified condition, rather than fetching all the data from the database. This can significantly reduce the amount of data transferred between the database server and the PHP application, leading to improved performance. 

// Using a "select count" query to check for existing data
$query = "SELECT COUNT(*) FROM table_name WHERE condition = 'value'";
$result = mysqli_query($connection, $query);
$row = mysqli_fetch_array($result);

if ($row[0] > 0) {
    // Data exists
    echo "Data exists in the database.";
} else {
    // Data does not exist
    echo "Data does not exist in the database.";
}

Keywords

select count select * query efficiency existing data PHP

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