Come ottenere un conteggio anche se non ci sono risultati corrispondenti mysql?

Question

Sto formalizzando una query per fornire il numero di rapporti inviati nell'ultimo anno ordinati per data. Ho l'anno e il mese corrente con php:

$year = date('Y') - 1; 
$month = date('m'); 

ed eseguire la seguente query: SQL:

SELECT month(date_lm) AS `month` , 
count(*) AS `count` 
FROM `reports` 
WHERE (status = 'submitted') 
AND (date_lm > 2012-08) 
GROUP BY month(date_lm) 
ORDER BY month(date_lm) ASC 

E perché c'è stato solo 1 presentata l'anno scorso mi dà solo 1 risultato ...

| month | count | 
| 7 | 1 | 

Ma vorrei il set di risultati per mostrare:

| month | count | 
| 9 | 0 | 
| 10 | 0 | 
| 11 | 0 | 
| 12 | 0 | 
| 1 | 0 | 
| 2 | 0 | 
| 3 | 0 | 
| 4 | 0 | 
| 5 | 0 | 
| 6 | 0 | 
| 7 | 1 | 
| 8 | 0 | 

È possibile?

Answer 1

Si dovrebbe LEFT JOIN questo tavolo con 1..12 tavolo. Qualcosa di simile a questo:

SELECT Months.id AS `month` , 
COUNT(`reports`.date_lm) AS `count` 
FROM 
(
    SELECT 1 as ID UNION SELECT 2 as ID UNION SELECT 3 as ID UNION SELECT 4 as ID 
    UNION 
    SELECT 5 as ID UNION SELECT 6 as ID UNION SELECT 7 as ID UNION SELECT 8 as ID 
    UNION 
    SELECT 9 as ID UNION SELECT 10 as ID UNION SELECT 11 as ID UNION SELECT 12 as ID 
) as Months 
LEFT JOIN `reports` on Months.id=month(`reports`.date_lm) 
         AND 
         (status = 'submitted') 
         AND (date_lm > 2012-08) 
GROUP BY Months.id 
ORDER BY Months.id ASC 

SQL Fiddle demo

Answer 2

Per fare ciò, è possibile creare una tabella "mese" e quindi utilizzare un join esterno sinistro tra quella tabella e la tabella dei report.

non ho mai usato mysql in modo scuse se la sintassi è leggermente fuori, ma questa sarebbe la query:

SELECT months.monthNumber, 
    count(reports.id) AS `count` 
FROM `months` left outer join `reports` on months.monthNumber = month(reports.date_lm) 
WHERE (status = 'submitted') 
AND (date_lm > 2012-08) 
GROUP BY monthNumber 
ORDER BY monthNumber ASC 

È importante sottolineare che il conteggio dovrebbe essere di una colonna della tabella rapporti, non i mesi tabella, altrimenti non otterresti mai uno zero.

Answer 3

count (nome_col) AS count vi darà contano 0

Come riferimento si può visitare http://www.mysqlperformanceblog.com/2007/04/10/count-vs-countcol/

Answer 4

Spero che questo possa aiutare ..

SELECT t1.month_year AS month, COALESCE(SUM(t1.total+t2.total), 0) AS count FROM ( SELECT DATE_FORMAT(a.Date, "%Y-%m") AS md, DATE_FORMAT(a.Date, "%b-%y") AS month_year, '0' AS total FROM ( SELECT curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY AS Date FROM (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS a CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS b CROSS JOIN (SELECT 0 AS a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) AS c ) a WHERE a.Date <= NOW() AND a.Date >= Date_add(Now(),INTERVAL - 11 MONTH) GROUP BY md )t1 LEFT JOIN ( SELECT DATE_FORMAT(created_at, "%b") AS month, COUNT(*) AS total ,DATE_FORMAT(created_at, "%Y-%m") AS md FROM reports WHERE created_at <= NOW() AND created_at >= Date_add(Now(),INTERVAL - 11 MONTH) AND stato = 1 GROUP BY md )t2 ON t2.md = t1.md LEFT JOIN ( SELECT DATE_FORMAT(date_lm, "%b") AS month, COUNT(*) AS total ,DATE_FORMAT(date_lm, "%Y-%m") AS md FROM tbl_users WHERE date_lm <= NOW() AND date_lm >= Date_add(Now(),INTERVAL - 11 MONTH) AND status = 'submitted' GROUP BY md )t3 ON t3.md = t1.md GROUP BY t1.md ORDER BY t1.md

questo darà i dati degli ultimi 12 mesi, anche se non ci sono dati per esso con un 0 ..