mysql - 计算计数组的平均值

Question

SELECT DATE( DATE ) DATE, COUNT( number ) totalCOunt
FROM numbers
GROUP BY DATE( DATE ) 
LIMIT 0 , 30

   DATE    totalCOunt
2013-01-01 13
2013-01-02 12
2013-01-03 22
2013-01-04 14
2013-01-05 14
2013-01-06 16
2013-01-07 13
2013-01-08 22
etc

如何获得这些数据的平均值？我多次尝试失败，我可以在 sql 或 foreach php 函数中执行此操作，但似乎 sql 查询执行速度会更快？

Answer 1

使用子选择:

SELECT AVG(totalCount) FROM (
    SELECT DATE( DATE ) DATE, COUNT( number ) totalCOunt
    FROM numbers
    GROUP BY DATE( DATE ) 
    LIMIT 0 , 30) TBL1