Get count of rows limit value sql php

问题

I have an sql table trade with following data

  id| value
   1| 0.1
   2| 0.5
   3| 0.9
   4| 0.3

How do I make an SQL query so that i get the count of entries limited to total value of 0.8 ascending by id in php. For example:-

COUNT id FROM trade WHERE SUM(value) > 0.8 by id ASC

Result should come as

回答1:

You need to do cumulative judgment,due to your mysql version didn't support window function so the solution will be a little hard to read,becuase you need to write subquery instead of window function.

make the cumulative number by Id column, then get the MIN(ID) in subquery, when Id = 3 the value will greater than 0.8.

finally get the Id small and equal the MIN(ID) you will get your expect result.

CREATE TABLE trade(
   id  INT,
    value FLOAT
);

INSERT INTO trade VALUES(1,0.1);
INSERT INTO trade VALUES(2,0.5);
INSERT INTO trade VALUES(3,0.9);
INSERT INTO trade VALUES(4,0.3);

Query 1:

SELECT COUNT(*)
FROM trade t1
WHERE t1.id <= (
SELECT MIN(ID) FROM (
 SELECT ID,(
    SELECT SUM(tt.value) 
    FROM trade tt
    WHERE tt.id <= t1.id  
  ) total
  FROM trade t1
) t1
where total > 0.8
)

Results:

| COUNT(*) |
|----------|
|        3 |

回答2:

It seems to me you need aggregate function and cumulative sum need to filter your desired result

 set @csum := 0.0;
select count(id) from
(

select id,@csum := @csum + value as sum_val   from t 
 order by id
 ) t1
where  sum_val <1.3

http://sqlfiddle.com/#!9/abf460/2

count(id)
 3

来源：https://stackoverflow.com/questions/52146199/get-count-of-rows-limit-value-sql-php

标签

php

mysql

sql

cumulative-sum