[SQL practice] a SQL statistics of epidemic distribution across the country

 

 

 

-- Epidemic situation table , Three fields ： City / region Province Current confirmed number
DROP TABLE IF EXISTS yiqing;
CREATE TABLE `datacenter`.`yiqing`(
`city` VARCHAR(32) COMMENT ' City / region ',
`province` VARCHAR(32) COMMENT ' Province ',
`current` INT COMMENT ' Current confirmed number '
)
COMMENT=' Epidemic information table ';

INSERT INTO yiqing
SELECT ' Jinnan District ', ' tianjin ', 217 UNION ALL
SELECT ' anyang ', ' shaanxi ', 110 UNION ALL
SELECT ' Xi'an ', ' shaanxi ', 1385 UNION ALL
SELECT ' xianyang ', ' Henan ', 10 UNION ALL
SELECT ' zhengzhou ', ' Henan ', 138 UNION ALL
SELECT ' Nanyang ', ' Henan ', 95 UNION ALL
SELECT ' The hulunbuir ', ' Inner Mongolia ', 5 UNION ALL
SELECT ' ningbo ', ' Zhejiang ', 55 UNION ALL
SELECT ' kaifeng ', ' Henan ', 5 UNION ALL
SELECT ' jinhua ', ' Zhejiang ', 3 UNION ALL
SELECT ' port of fangcheng ', ' guangxi ', 2 UNION ALL
SELECT ' zhongshan ', ' guangdong ', 51 UNION ALL
SELECT ' dalian ', ' liaoning ', 3 ;

SELECT * FROM yiqing ORDER BY 2,1;

 

 

-- §§§【 Statistics on the distribution of epidemic situation in the country Result column ： Province 、 Severity level 、 Cumulative number of confirmed cases 】
SELECT province AS ' Province '
, CASE WHEN SUM(current)>=100 THEN 'Level1' WHEN SUM(current)<100 AND SUM(current)>=50 THEN 'Level2' ELSE 'Levy3' END AS ' severity '
, SUM(current) AS ' Cumulative confirmed number '
FROM yiqing
GROUP BY province
ORDER BY 3 DESC;

 

 

-- §§§【 Statistics on the distribution of epidemic situation in various provinces Result column ： Province 、 Epidemic risk level 、 Number of urban areas 、 Current confirmed number . for example ： Henan Province has 3 A high-risk city , The total number of confirmed cases 300 people 】
SELECT province AS ' Province '
, CASE WHEN current>=100 THEN ' high '
WHEN current>=50 AND current<100 THEN ' in '
ELSE ' low ' END AS ' Epidemic risk level '
, COUNT(1) AS ' Number of urban areas '
, SUM(current) AS ' Current confirmed number '
FROM yiqing
GROUP BY province, CASE WHEN current>=100 THEN ' high '
WHEN current>=50 AND current<100 THEN ' in '
ELSE ' low ' END
ORDER BY 1, CASE Epidemic risk level WHEN ' high ' THEN 1 WHEN ' in ' THEN 2 ELSE 3 END;