一、問題
故事起源于一個(gè)查詢錯(cuò)漏率的報(bào)表：有兩個(gè)查詢結(jié)果，分別是報(bào)告已經(jīng)添加的項(xiàng)目和報(bào)告應(yīng)該添加的項(xiàng)目，求報(bào)告無遺漏率
何為無遺漏？即，應(yīng)該添加的項(xiàng)目已經(jīng)被全部添加
報(bào)告無遺漏率也就是無遺漏報(bào)告數(shù)占報(bào)告總數(shù)的比率
這里以兩個(gè)報(bào)告示例（分別是已全部添加和有遺漏的報(bào)告）
首先，查出第一個(gè)結(jié)果——報(bào)告應(yīng)該添加的項(xiàng)目
SELECT
r.id AS 報(bào)告ID,m.project_id 應(yīng)添加項(xiàng)目
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
RIGHT JOIN application_sample_item si ON s.id=si.sample_id
RIGHT JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id;
然后，再查出第二個(gè)結(jié)果——報(bào)告已經(jīng)添加的項(xiàng)目
SELECT r.id AS 報(bào)告ID,i.project_id AS 已添加項(xiàng)目
FROM report r
RIGHT JOIN report_item i ON r.id=i.report_id
WHERE r.id IN ('44930','44927');
以上就是我們要比較的結(jié)果集，不難看出報(bào)告44927是無遺漏的，而44930雖然項(xiàng)目數(shù)量一致，但實(shí)際是多添加了項(xiàng)目758，缺少了項(xiàng)目112，是有遺漏的報(bào)告
二、解決方案
從問題看，顯然是一個(gè)判斷是否為子集的問題。可以分別遍歷已添加的項(xiàng)目和應(yīng)該添加的項(xiàng)目，如果應(yīng)該添加的項(xiàng)目在已添加的項(xiàng)目中都能匹配上，即代表應(yīng)該添加的項(xiàng)目是已添加的項(xiàng)目子集，也就是無遺漏。
通過循環(huán)遍歷比較確實(shí)可以解決這個(gè)問題，但是SQL中出現(xiàn)笛卡兒積的交叉連接往往意味著開銷巨大，查詢速度慢，那么有沒有辦法避免這一問題呢？
方案一：
借助于函數(shù) FIND_IN_SET和GROUP_CONCAT, 首先認(rèn)識(shí)下兩個(gè)函數(shù)
FIND_IN_SET(str,strlist)
- str: 需要查詢的字符串
- strlist: 參數(shù)以英文”,”分隔，如 (1,2,6,8,10,22)
FIND_IN_SET 函數(shù)返回了需要查詢的字符串在目標(biāo)字符串的位置
GROUP_CONCAT( [distinct] 要連接的字段 [order by 排序字段 asc/desc ] [separator '分隔符'] )
GROUP_CONCAT()函數(shù)可以將多條記錄的同一字段的值，拼接成一條記錄返回。默認(rèn)以英文‘,'分割。
但是，GROUP_CONCAT()默認(rèn)長(zhǎng)度為1024
所以，如果需要拼接的長(zhǎng)度超過1024將會(huì)導(dǎo)致截取不全，需要修改長(zhǎng)度
SET GLOBAL group_concat_max_len=102400;
SET SESSION group_concat_max_len=102400;
從上述兩個(gè)函數(shù)介紹中，我們發(fā)現(xiàn)FIND_IN_SET和GROUP_CONCAT都以英文‘,'分割（加粗標(biāo)識(shí)）
所以，我們可以用GROUP_CONCAT將已添加項(xiàng)目的項(xiàng)目連接為一個(gè)字符串，然后再用FIND_IN_SET逐一查詢應(yīng)添加項(xiàng)目是否都存在于字符串
1、修改問題中描述中的SQL，用GROUP_CONCAT將已添加項(xiàng)目的項(xiàng)目連接為一個(gè)字符串
SELECT r.id,GROUP_CONCAT(i.project_id ORDER BY i.project_id,'') AS 已添加項(xiàng)目列表
FROM report r
LEFT JOIN report_item i ON r.id=i.report_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id;
2、用FIND_IN_SET逐一查詢應(yīng)添加項(xiàng)目是否都存在于字符串
SELECT Q.id,FIND_IN_SET(W.應(yīng)添加項(xiàng)目列表,Q.已添加項(xiàng)目列表) AS 是否遺漏
FROM
(
-- 報(bào)告已經(jīng)添加的項(xiàng)目
SELECT r.id,GROUP_CONCAT(i.project_id ORDER BY i.project_id,'') AS 已添加項(xiàng)目列表
FROM report r
LEFT JOIN report_item i ON r.id=i.report_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id
)Q,
(
-- 報(bào)告應(yīng)該添加的項(xiàng)目
SELECT
r.id,s.app_id,m.project_id 應(yīng)添加項(xiàng)目列表
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)W
WHERE Q.id=W.id;
3、過濾掉有遺漏的報(bào)告
SELECT Q.id,CASE WHEN FIND_IN_SET(W.應(yīng)添加項(xiàng)目列表,Q.已添加項(xiàng)目列表)>0 THEN 1 ELSE 0 END AS 是否遺漏
FROM
(
-- 報(bào)告已經(jīng)添加的項(xiàng)目
SELECT r.id,GROUP_CONCAT(i.project_id ORDER BY i.project_id,'') AS 已添加項(xiàng)目列表
FROM report r
LEFT JOIN report_item i ON r.id=i.report_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id
)Q,
(
-- 報(bào)告應(yīng)該添加的項(xiàng)目
SELECT
r.id,s.app_id,m.project_id 應(yīng)添加項(xiàng)目列表
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)W
WHERE Q.id=W.id
GROUP BY Q.id
HAVING COUNT(`是否遺漏`)=SUM(`是否遺漏`);
4、我們的最終目標(biāo)是求無遺漏率
SELECT COUNT(X.id) 無遺漏報(bào)告數(shù),Y.total 報(bào)告總數(shù), CONCAT(FORMAT(COUNT(X.id)/Y.total*100,2),'%') AS 項(xiàng)目無遺漏率 FROM
(
SELECT Q.id,CASE WHEN FIND_IN_SET(W.應(yīng)添加項(xiàng)目列表,Q.已添加項(xiàng)目列表)>0 THEN 1 ELSE 0 END AS 是否遺漏
FROM
(
-- 報(bào)告已經(jīng)添加的項(xiàng)目
SELECT r.id,GROUP_CONCAT(i.project_id ORDER BY i.project_id,'') AS 已添加項(xiàng)目列表
FROM report r
LEFT JOIN report_item i ON r.id=i.report_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id
)Q,
(
-- 報(bào)告應(yīng)該添加的項(xiàng)目
SELECT
r.id,s.app_id,m.project_id 應(yīng)添加項(xiàng)目列表
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)W
WHERE Q.id=W.id
GROUP BY Q.id
HAVING COUNT(`是否遺漏`)=SUM(`是否遺漏`)
)X,
(
-- 總報(bào)告數(shù)
SELECT COUNT(E.nums) AS total FROM
(
SELECT COUNT(r.id) AS nums FROM report r
WHERE r.id IN ('44930','44927')
GROUP BY r.id
)E
)Y
;
方案二：
上述方案一雖然避免了逐行遍歷對(duì)比，但本質(zhì)上還是對(duì)項(xiàng)目的逐一對(duì)比，那么有沒有什么方式可以不用對(duì)比呢？
答案當(dāng)然是有的。我們可以根據(jù)統(tǒng)計(jì)數(shù)量判斷是否完全包含。
1、使用union all 將已添加項(xiàng)目與應(yīng)添加項(xiàng)目聯(lián)表，不去重
(
-- 應(yīng)該添加的項(xiàng)目
SELECT
r.id,m.project_id
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)
UNION ALL
(
-- 已經(jīng)添加的項(xiàng)目
select r.id,i.project_id from report r,report_item i
where r.id = i.report_id and r.id IN ('44930','44927')
group by r.app_id,i.project_id
)
從結(jié)果可以看出，項(xiàng)目同一個(gè)報(bào)告下有重復(fù)的項(xiàng)目，分別代表了應(yīng)該添加和已經(jīng)添加的項(xiàng)目
2、根據(jù)聯(lián)表結(jié)果，統(tǒng)計(jì)報(bào)告重合的項(xiàng)目數(shù)量
# 應(yīng)該添加與已經(jīng)添加的項(xiàng)目重疊數(shù)量
select tt.id,count(*) count from
(
select t.id,t.project_id,count(*) from
(
(
-- 應(yīng)該添加的項(xiàng)目
SELECT
r.id,m.project_id
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)
UNION ALL
(
-- 已經(jīng)添加的項(xiàng)目
select r.id,i.project_id from report r,report_item i
where r.id = i.report_id and r.id IN ('44930','44927')
group by r.app_id,i.project_id
)
) t
GROUP BY t.id,t.project_id
HAVING count(*) >1
) tt group by tt.id
3、將第二步的數(shù)量與應(yīng)該添加的數(shù)量作比較，如果相等，則代表無遺漏
select bb.id,aa.count 已添加,bb.count 需添加,
CASE WHEN aa.count/bb.count=1 THEN 1
ELSE 0
END AS '是否遺漏'
from
(
# 應(yīng)該添加與已經(jīng)添加的項(xiàng)目重疊數(shù)量
select tt.id,count(*) count from
(
select t.id,t.project_id,count(*) from
(
(
-- 應(yīng)該添加的項(xiàng)目
SELECT
r.id,m.project_id
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)
UNION ALL
(
-- 已經(jīng)添加的項(xiàng)目
select r.id,i.project_id from report r,report_item i
where r.id = i.report_id and r.id IN ('44930','44927')
group by r.app_id,i.project_id
)
) t
GROUP BY t.id,t.project_id
HAVING count(*) >1
) tt group by tt.id
) aa RIGHT JOIN
(
-- 應(yīng)該添加的項(xiàng)目數(shù)量
SELECT
r.id,s.app_id,COUNT(m.project_id) count
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id
ORDER BY r.id,m.project_id
) bb ON aa.id = bb.id
ORDER BY aa.id
4、求出無遺漏率
select
SUM(asr.`是否遺漏`) AS 無遺漏數(shù),COUNT(asr.id) AS 總數(shù),CONCAT(FORMAT(SUM(asr.`是否遺漏`)/COUNT(asr.id)*100,5),'%') AS 報(bào)告無遺漏率
from
(
select bb.id,aa.count 已添加,bb.count 需添加,
CASE WHEN aa.count/bb.count=1 THEN 1
ELSE 0
END AS '是否遺漏'
from
(
# 應(yīng)該添加與已經(jīng)添加的項(xiàng)目重疊數(shù)量
select tt.id,count(*) count from
(
select t.id,t.project_id,count(*) from
(
(
-- 應(yīng)該添加的項(xiàng)目
SELECT
r.id,m.project_id
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
ORDER BY r.id,m.project_id
)
UNION ALL
(
-- 已經(jīng)添加的項(xiàng)目
select r.id,i.project_id from report r,report_item i
where r.id = i.report_id and r.id IN ('44930','44927')
group by r.app_id,i.project_id
)
) t
GROUP BY t.id,t.project_id
HAVING count(*) >1
) tt group by tt.id
) aa RIGHT JOIN
(
-- 應(yīng)該添加的項(xiàng)目數(shù)量
SELECT
r.id,s.app_id,COUNT(m.project_id) count
FROM
report r
INNER JOIN application a ON r.app_id=a.id
INNER JOIN application_sample s ON a.id=s.app_id
INNER JOIN application_sample_item si ON s.id=si.sample_id
INNER JOIN set_project_mapping m ON si.set_id=m.set_id
WHERE r.id IN ('44930','44927')
GROUP BY r.id
ORDER BY r.id,m.project_id
) bb ON aa.id = bb.id
ORDER BY aa.id
) asr;
到此這篇關(guān)于mysql 判斷是否為子集的方法步驟的文章就介紹到這了,更多相關(guān)mysql 判斷是否子集內(nèi)容請(qǐng)搜索腳本之家以前的文章或繼續(xù)瀏覽下面的相關(guān)文章希望大家以后多多支持腳本之家！
您可能感興趣的文章:- MySql8 WITH RECURSIVE遞歸查詢父子集的方法
