SELECT a.date,a.tag,ROUND(a.err_hit/b.total *100,2)  as percent
FROM 
(
SELECT date as date ,
tag,
sum(hit) as err_hit
FROM ludeo.annual_report
WHERE date >= DATE_SUB(CURDATE(), INTERVAL 30 DAY)  AND status = -1 AND failed_cause != 0  
GROUP BY date,tag
)AS a
LEFT JOIN
(
SELECT date as date ,
tag,
 

sum(hit) as total
FROM ludeo.annual_report
WHERE date >= DATE_SUB(CURDATE(), INTERVAL 30 DAY) 
GROUP BY date,tag
) AS b ON a.date = b.date and a.tag = b.tag;