MySQL实现累加、累乘、累减、累除
table: TEST+-----------+---------+---------+| PARENT_ID | PART_ID | QUALITY |+-----------+---------+---------+| 1 | 1 | 2 || 1 | 2 | 3 || 1 | 3 | 2 || 1 | 4 | 5 || 2 | 2 | 3 || 2 | 3 | 5 || 2 | 4 | 7 |+-----------+---------+---------+累加
最简略，用sum+over即可
SELECT T.*, SUM(T.QUALITY) OVER (PARTITION BY T.PARENT_ID ORDER BY T.PART_ID) RUNNING_QUALITYFROM TEST T;累乘
应用EXP(SUM(LN(字段))实现累乘，其余的和累加一样！
SELECT T.*, ROUND(EXP(SUM(LN(T.QUALITY)) OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID)),0) RUNNING_PRODFROM TEST T;累减
累减巧用负号！
（1）先用row_number排序
SELECT T.*, ROW_NUMBER() OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID) RNFROM TEST T+-----------+---------+---------+----+| PARENT_ID | PART_ID | QUALITY | RN |+-----------+---------+---------+----+| 1 | 1 | 2 | 1 || 1 | 2 | 3 | 2 || 1 | 3 | 2 | 3 || 1 | 4 | 5 | 4 || 2 | 2 | 3 | 1 || 2 | 3 | 5 | 2 || 2 | 4 | 7 | 3 |+-----------+---------+---------+----+（2）当RN=1时，保留第一位的数字，其余的全副取负号，这样就能够实现累减了！
SELECT T.PARENT_ID, T.PART_ID, T.QUALITY, SUM(if(T.RN=1,T.QUALITY,-T.QUALITY)) OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID) RUNNING_PRODFROM ( SELECT T.*, ROW_NUMBER() OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID) RN FROM TEST T) T;累除
和累减相似，只不过这里要把非第一位的数字，取对数后再取负号，这样通过sum和exp就相当于做除法啦！
SELECT T.PARENT_ID, T.PART_ID, T.QUALITY, round(EXP(SUM(if(RN=1,LN(T.QUALITY),-LN(T.QUALITY))) OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID)),2) RUNNING_PRODFROM ( SELECT T.*, ROW_NUMBER() OVER(PARTITION BY T.PARENT_ID ORDER BY T.PART_ID) RN FROM TEST T)T;- 小红书：鲸鲸说数据
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