SQL stament groups rows and calculate average - mysql

Question

I am stuck with the following issue. I have 1 table that looks like this:
field_number.. Value
````````````````````````````````
1 ......................... 1
2 ..........................1
3 ......................... 2
4 ..........................2
etc.
I want to group different fieldnumbers and have an average for the value column. So the output should be:
field_number................Value
name(1,2)...................... 1.............. ((1+1)/2)
name(3,4)...................... 2.............. ((2+2)/2)
I have checked previous questions but cannot find any question that covers this issue (I might search on the wrong keywords though). So if this has already been covered my appologies, but any help or a point to a previous answer would be appreciated.
** =============UPDATE============= **
I went through your suggestions but did not get it right. So I am trying to be more specific. I almost have the result I want apart from the fact I want to have a fixed value in one of my columns. I have the following query:
Select
Avg(wp_rg_lead_detail.value),
wp_rg_lead_detail.field_number,
From
wp_rg_lead_detail
Where
wp_rg_lead_detail.field_number In (15, 17, 24) A
UNION
Select
Avg(wp_rg_lead_detail.value),
wp_rg_lead_detail.field_number,
From
wp_rg_lead_detail
Where
wp_rg_lead_detail.field_number In (16, 108, 18)
etc.
This gives me a table with two columns
wp_rg_lead_detail.value................field_number
4.3 (average)..............................15 (first value of av calculation)
What I want is to change the field number (15 in this case) in a fixed value (text). What and how should I add this to the query?

Answer 1

SELECT avg(value) FROM table WHERE field_number in (1,2)
SELECT avg(value) FROM table WHERE field_number in (3,4)

Answer 2

If your table is really this simple, you can also get away with:
select distinct
Value,
count(Value) as '#'
from table_name
group by Value
If you acctually want to group by a range, than you can put the logic of the range in your grouping clause (see this fiddle)
select distinct
avg(Value) as average,
floor(Value),
count(Value) as '#'
from table_name
group by floor(Value)
In the fiddle I used grouping on whole integers, but you can make that as complex as you like (see, for instance, this example)
If you are actually also interested in your corresponding fields, use group_concat() like so
select
Value,
group_concat(
distinct field_number
order by Value
) as fields
from table_name tn1
group by Value
order by Value
output:
Value | fields
---------------------------------
1 | 1,2
2 | 3,4
See this fiddle implemented from this blog post

Answer 3

For a generalized answer.
SELECT CONCAT('name','(',GROUP_CONCAT(field_number),')') AS field_number,
AVG(Value) as Value
FROM table_name
group by table_name.`Value`
Hope this helps.