PHP & MySQL: Group query results and take averages

Question

I have data in the following format:

1/1/2017   55
1/3/2017   23
1/3/2017   87
1/3/2017   45
1/4/2017   77
1/4/2017   90
1/4/2017   34

What is the fasted and most efficient way to query the database and output the average value for each date?

Answer 1

Your question is missing a lot of information and shows little or no effort in solving the problem.

Regardless, you can use a SQL query like this to achieve the results you want:

SELECT date_col, AVG(number_col) as average FROM table_name GROUP BY date_col

Answer 2

尝试这个

SELECT avg(value_field) FROM `table_name` group by date _field