Counting number of grouped rows in mysql

Question

In a table xyz I have a row called components and a labref row which has labref number as shown here

Table xyz

labref             component
NDQA201303001         


        

Answer 1

Why not use num_rows.

If you do it using this method, You don't have to modify the query in any way.

if ($result = $mysqli->query("SELECT DISTINCT component, COUNT( component ) 
    FROM `xyz`
    WHERE labref = 'NDQA201303001'
    GROUP BY component")){

    /* determine number of rows result set */
    $row_cnt = $result->num_rows;

    printf("Result set has %d rows.\n", $row_cnt);

    /* close result set */
    $result->close();
}