在PHP中创建mySQL查询以生成列平均值的JSON数组

Question

I'm trying to create a PHP script that will echo the average value of each of my columns and array them all in a single JSON array.

I know that this is how I can get the average for a column.

select avg(`sales`) as sales  from `mytable`

But I'm not sure how to string this together

select avg(`sales`) as sales  from `mytable`
select avg(`profit`) as profit  from `mytable`
select avg(`costs`) as costs  from `mytable`

To get something like this echo'd from PHP:

[
{
    "sales": 56812
},
{
    "profit": 2312
},
{
    "costs": 324
}
]

Answer 1

You're close.

select
    avg(sales) as sales,
    avg(profit) as profit,
    avg(costs) as costs
from mytable;

Note that I removed the backticks around your column and table names because they are not necessary and are just visual noise and are one other thing to make mistakes about.