count行與特定值

Question

我有一個表名PHP是TB1

tb1 
id zone pressure 
1 India Yes 
2 USA No 
3 UK Yes 
4 India Yes 
5 AUS No 
6 UK Yes 

壓力有兩個有點像「是」和「否」我需要導致以這種方式進入的

Zone Pressure 
     Yes No 
India 2 0 
USA  0 1 
UK  1 1 
AUS  0 1 

我的努力到目前爲止...

$result = mysql_query("SELECT Zone FROM Tb1 WHERE Pressure = 'Yes'"); 
$num_rows = mysql_num_rows($result); echo $num_rows . " \n"; 

Answer 1

SELECT zone, 
     SUM(pressure = 'Yes') AS `Yes`, 
     SUM(pressure = 'No') AS `No` 
    FROM tb1 
GROUP BY zone 

你需要的技巧。這是一個聚合查詢。這是一個小提琴。 http://sqlfiddle.com/#!2/54889/2/0

Answer 2

你可以做

select tb1.zone, 
sum(tb1.pressure = 'Yes') as Yes, 
sum(tb1.pressure = 'No') as No 
from tb1 
group by tb1.zone 

Answer 3

SELECT zone 
    , SUM(pressure='yes') yes 
    , SUM(pressure='no') no 
    FROM my_table 
GROUP 
    BY zone; 

Answer 4

SELECT Zone, 
     SUM(pressure='Yes') as `Yes`, 
     SUM(pressure='No') as `No` 
FROM Tb1 
GROUP BY Zone;