简化此查询

Question

SELECT COUNT( sendbook.id ) AS total, SUM( sendbook.num ) AS num, (

SELECT COUNT( sendbook.id )
FROM sendbook
INNER JOIN clients ON clients.id = sendbook.clientid
WHERE sendbook.issueid = '29'
AND clients.area >1000
AND clients.area <2000
) AS area1000, (

SELECT COUNT( sendbook.id )
FROM sendbook
INNER JOIN clients ON clients.id = sendbook.clientid
WHERE sendbook.issueid = '29'
AND clients.area >2000
AND clients.area <3000
) AS area2000, (

SELECT COUNT( sendbook.id )
FROM sendbook
INNER JOIN clients ON clients.id = sendbook.clientid
WHERE sendbook.issueid = '29'
AND clients.area >3000
AND clients.area <4001
) AS area2000
FROM `sendbook`
WHERE sendbook.issueid = '29' 

total  num  area1000  area2000  area2000
 8      438      3         3        2

您知道一种简化此查询的方法吗？ 认为

Answer 1

你需要使用类似这样的case语句：

SELECT  COUNT( sendbook.id ),
(CASE 
WHEN clients.area between '1000' and '2000'  THEN 1 
WHEN clients.area between '2000' and '3000'  THEN 2 
WHEN clients.area between '3000' and '4000'  THEN 3 
 END) AS myrange  FROM mytable 
GROUP BY myrange