mysql counting rows with loop

Question

I have the following table:

+-------------+--------------+ 
| product     | purchased    |
+-------------+--------------+ 
| Hammer      |   |
|         


        

Answer 1

What you need to work with is whether the warranty is still valid or expired and the warranty date, so you first need to build a table that reflects that:

select   product
       , IF( warranty >= NOW(), 1, 0 ) as valid
       , IF( warranty < NOW(), 1, 0 ) as expired
       , warranty as last
from     (
           select   product
                ,   ADDDATE( purchased, INTERVAL 5 YEAR ) as warranty
           from     productWarranty
         ) w
group by product
;

That would get you something like that:

+---------+-------+---------+---------------------+
| product | valid | expired | warranty            |
+---------+-------+---------+---------------------+
| Hammer  |     1 |       0 | 2017-01-01 00:00:00 |
| Nipper  |     1 |       0 | 2017-01-01 00:00:00 |
| Nipper  |     1 |       0 | 2017-01-01 00:00:00 |
| Nipper  |     1 |       0 | 2017-01-01 00:00:00 |
| Saw     |     1 |       0 | 2017-01-01 00:00:00 |
| Saw     |     0 |       1 | 2011-01-01 00:00:00 |
| Saw     |     1 |       0 | 2017-01-01 00:00:00 |
| Saw     |     1 |       0 | 2017-01-01 00:00:00 |
+---------+-------+---------+---------------------+

Then use aggregate functions to filter and sum up the information you're looking for:

select   product
       , SUM( IF( warranty >= NOW(), 1, 0 ) ) as valid
       , SUM( IF( warranty < NOW(), 1, 0 ) ) as expired
       , MAX( warranty ) as last
from     (
           select   product
                  , affffdate( purchased, interval 5 year ) as warranty
           from productWarranty
         ) w
group by product
;

+---------+-------+---------+---------------------+
| product | valid | expired | last                |
+---------+-------+---------+---------------------+
| Hammer  |     1 |       0 | 2017-01-01 00:00:00 |
| Nipper  |     3 |       0 | 2017-01-01 00:00:00 |
| Saw     |     3 |       1 | 2017-01-01 00:00:00 |
+---------+-------+---------+---------------------+

Answer 2

Here's the answer I posted in your other question

SELECT  p2c.pid AS productNumber,
        p.name AS productName,
        COUNT(*) AS registered,
        SUM(date_add(from_unixtime(purchased), INTERVAL 5 YEAR) >= CURDATE()) AS inWarranty,
        SUM(date_add(from_unixtime(purchased), INTERVAL 5 YEAR) < CURDATE()) AS outOfWarranty,
        DATE_FORMAT( MAX( from_unixtime(purchased) ), '%d.%m.%Y') AS lastPurchased,
        DATE_FORMAT( date_add( MAX( from_unixtime(purchased) ), INTERVAL 5 YEAR), '%d.%m.%Y') AS warrantyUntil
FROM products2customers p2c
JOIN products p ON p.id = p2c.pid
GROUP BY p2c.pid
ORDER BY inWarranty DESC

Answer 3

Better normalization would speed up this query tremendously, but here's an example to work from:

First, you need to start with your base query, the one that will drive the results. In this case, it's a list of all the products in your table:

SELECT DISTINCT product
FROM   productWarranty

The above query creates a sort of "temp" table that we can base our queries on. If you have a separate, normalized product table then that would be much better.

The rest of the columns can simply be subqueries driven by your base table:

Total count:

SELECT COUNT(*)
FROM   productWarranty
WHERE  product = 'Hammer'

Total valid warranties:

SELECT COUNT(*)
FROM   productWarranty
WHERE  product = 'Hammer'
   AND purchased >= <warranty cut-off date>

Total expired warranties:

SELECT COUNT(*)
FROM   productWarranty
WHERE  product = 'Hammer'
   AND purchased < <warranty cut-off date>

Last purchase date:

SELECT MAX( purchased )
FROM   productWarranty
WHERE  product = 'Hammer'

Now to combine all of these into a single query:

SELECT  Base.product
    ,   (
            SELECT COUNT(*)
            FROM   productWarranty
            WHERE  product = Base.product
        ) AS TotalCount
    ,   (
            SELECT COUNT(*)
            FROM   productWarranty
            WHERE  product = Base.product
               AND date_add(from_unixtime(purchased), INTERVAL 5 YEAR) >= CURDATE()
        ) AS ValidWarrantyCount
    ,   (    
            SELECT COUNT(*)
            FROM   productWarranty
            WHERE  product = Base.product
               AND date_add(from_unixtime(purchased), INTERVAL 5 YEAR) < CURDATE()
        ) AS ExpiredWarrantyCount
    ,   (
            SELECT MAX( purchased )
            FROM   productWarranty
            WHERE  product = Base.product
        ) AS LastPurchased
FROM    (
            SELECT DISTINCT product
            FROM   productWarranty
        ) AS Base