簡化查詢

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 

您是否知道簡化查詢的方法？ 思

Answer 1

你需要使用case語句是這樣的：

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