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* group by range of values
@ 2007-07-27 19:05 Carol Cheung <cacheung@consumercontact.com>
0 siblings, 3 replies; 6+ messages in thread
From: Carol Cheung @ 2007-07-27 19:05 UTC (permalink / raw)
To: pgsql-sql
Hello,
Here's my table:
db=# select * from tester order by birth_year;
birth_year | salary
------------+--------
1946 | 78000
1949 | 61000
1951 | 58000
1953 | 56000
1958 | 52000
1962 | 50000
1965 | 45000
1967 | 60000
1968 | 57000
1970 | 47000
1972 | 32000
1973 | 42000
(12 rows)
How can I display the average salary grouped by decade of birth year?
That is, is it possible to display the average salary of those born in
the 1940's, the average salary of those born in the 1950's, average
salary of those born in the 1960's, and those born in the 1970's, all in
one result table?
Something like:
decade | average(salary)
-------+-----------------
1940 | 69500
1950 | 53333.33
1960 | 53000
1970 | 40333.33
Thanks in advance,
C
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: group by range of values
@ 2007-07-27 19:25 Jon Sime <jsime@mediamatters.org>
parent: Carol Cheung <cacheung@consumercontact.com>
2 siblings, 0 replies; 6+ messages in thread
From: Jon Sime @ 2007-07-27 19:25 UTC (permalink / raw)
To: pgsql-sql
Carol Cheung wrote:
> Hello,
>
> Here's my table:
>
> db=# select * from tester order by birth_year;
> birth_year | salary
> ------------+--------
> 1946 | 78000
> 1949 | 61000
> 1951 | 58000
> 1953 | 56000
> 1958 | 52000
> 1962 | 50000
> 1965 | 45000
> 1967 | 60000
> 1968 | 57000
> 1970 | 47000
> 1972 | 32000
> 1973 | 42000
> (12 rows)
>
> How can I display the average salary grouped by decade of birth year?
> That is, is it possible to display the average salary of those born in
> the 1940's, the average salary of those born in the 1950's, average
> salary of those born in the 1960's, and those born in the 1970's, all in
> one result table?
> Something like:
>
> decade | average(salary)
> -------+-----------------
> 1940 | 69500
> 1950 | 53333.33
> 1960 | 53000
> 1970 | 40333.33
>
Assuming birth_year is an integer (if it's not, then just change the
query to cast it to one before the division), one possible approach
might be:
select birth_year / 10 || '0' as decade,
avg(salary::numeric) as average_salary
from tester
group by decade
order by decade asc;
-Jon
--
Senior Systems Developer
Media Matters for America
http://mediamatters.org/
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: group by range of values
@ 2007-07-27 19:28 Rodrigo De León <rdeleonp@gmail.com>
parent: Carol Cheung <cacheung@consumercontact.com>
2 siblings, 1 reply; 6+ messages in thread
From: Rodrigo De León @ 2007-07-27 19:28 UTC (permalink / raw)
To: Carol Cheung <cacheung@consumercontact.com>; +Cc: pgsql-sql
On 7/27/07, Carol Cheung <cacheung@consumercontact.com> wrote:
> Something like:
>
> decade | average(salary)
> -------+-----------------
> 1940 | 69500
> 1950 | 53333.33
> 1960 | 53000
> 1970 | 40333.33
CREATE TABLE tester (
birth_year integer,
salary numeric(10,2)
);
SELECT
SUBSTRING(TO_CHAR(BIRTH_YEAR,'FM9999') FROM 1 FOR 3)||'0'
AS DECADE
, AVG(SALARY) AS AVG_SALARY
FROM TESTER
GROUP BY
SUBSTRING(TO_CHAR(BIRTH_YEAR,'FM9999') FROM 1 FOR 3)||'0'
ORDER BY DECADE;
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: group by range of values
@ 2007-07-27 19:30 Pavel Stehule <pavel.stehule@gmail.com>
parent: Carol Cheung <cacheung@consumercontact.com>
2 siblings, 1 reply; 6+ messages in thread
From: Pavel Stehule @ 2007-07-27 19:30 UTC (permalink / raw)
To: Carol Cheung <cacheung@consumercontact.com>; +Cc: pgsql-sql
Hello
you can use CASE like
SELECT CASE
WHEN birth_year BETWEEN 1940 AND 1949 THEN 1940
WHEN birth_year BETWEEN 1950 AND 1959 THEN 1950
WHEN birth_year BETWEEN 1960 AND 1969 THEN 1960
WHEN birth_year BETWEEN 1970 AND 1979 THEN 1979 END, AVG(salary)
FROM tester GROUP BY 1 ORDER BY 1;
Regards
Pavel Stehule
2007/7/27, Carol Cheung <cacheung@consumercontact.com>:
> Hello,
>
> Here's my table:
>
> db=# select * from tester order by birth_year;
> birth_year | salary
> ------------+--------
> 1946 | 78000
> 1949 | 61000
> 1951 | 58000
> 1953 | 56000
> 1958 | 52000
> 1962 | 50000
> 1965 | 45000
> 1967 | 60000
> 1968 | 57000
> 1970 | 47000
> 1972 | 32000
> 1973 | 42000
> (12 rows)
>
> How can I display the average salary grouped by decade of birth year?
> That is, is it possible to display the average salary of those born in
> the 1940's, the average salary of those born in the 1950's, average
> salary of those born in the 1960's, and those born in the 1970's, all in
> one result table?
> Something like:
>
> decade | average(salary)
> -------+-----------------
> 1940 | 69500
> 1950 | 53333.33
> 1960 | 53000
> 1970 | 40333.33
>
> Thanks in advance,
> C
>
> ---------------------------(end of broadcast)---------------------------
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>
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: group by range of values
@ 2007-07-27 19:31 Rodrigo De León <rdeleonp@gmail.com>
parent: Rodrigo De León <rdeleonp@gmail.com>
0 siblings, 0 replies; 6+ messages in thread
From: Rodrigo De León @ 2007-07-27 19:31 UTC (permalink / raw)
To: Carol Cheung <cacheung@consumercontact.com>; +Cc: pgsql-sql
On 7/27/07, I wrote:
> On 7/27/07, Carol Cheung <cacheung@consumercontact.com> wrote:
> > Something like:
> >
> > decade | average(salary)
> > -------+-----------------
> > 1940 | 69500
> > 1950 | 53333.33
> > 1960 | 53000
> > 1970 | 40333.33
>
> CREATE TABLE tester (
> birth_year integer,
> salary numeric(10,2)
> );
>
> SELECT
> SUBSTRING(TO_CHAR(BIRTH_YEAR,'FM9999') FROM 1 FOR 3)||'0'
> AS DECADE
> , AVG(SALARY) AS AVG_SALARY
> FROM TESTER
> GROUP BY
> SUBSTRING(TO_CHAR(BIRTH_YEAR,'FM9999') FROM 1 FOR 3)||'0'
> ORDER BY DECADE;
A bit simpler, if year is int:
SELECT
BIRTH_YEAR/10*10
AS DECADE
, AVG(SALARY) AS AVG_SALARY
FROM TESTER
GROUP BY
BIRTH_YEAR/10*10
ORDER BY DECADE;
^ permalink raw reply [nested|flat] 6+ messages in thread
* Re: group by range of values
@ 2007-07-27 20:43 Michael Glaesemann <grzm@seespotcode.net>
parent: Pavel Stehule <pavel.stehule@gmail.com>
0 siblings, 0 replies; 6+ messages in thread
From: Michael Glaesemann @ 2007-07-27 20:43 UTC (permalink / raw)
To: Pavel Stehule <pavel.stehule@gmail.com>; +Cc: Carol Cheung <cacheung@consumercontact.com>; pgsql-sql
2007/7/27, Carol Cheung <cacheung@consumercontact.com>:
> db=# select * from tester order by birth_year;
> birth_year | salary
> ------------+--------
> 1946 | 78000
> 1949 | 61000
What is the data type of the birth_year column? I'd suggest using
date if you can, as what it is is a date with year precision. You
can't specify such a precision, but you can decide that all
birth_year's will have month and year of January 1 (enforced by a
CHECK constraint, if you wish), or you could just choose to ignore
the month and year part in your calculations.
> How can I display the average salary grouped by decade of birth year?
> That is, is it possible to display the average salary of those born in
> the 1940's, the average salary of those born in the 1950's, average
> salary of those born in the 1960's, and those born in the 1970's,
> all in
> one result table?
> Something like:
>
> decade | average(salary)
> -------+-----------------
> 1940 | 69500
> 1950 | 53333.33
> 1960 | 53000
> 1970 | 40333.33
Here's an example:
CREATE TABLE salaries (birth_year DATE PRIMARY KEY, salary NUMERIC
NOT NULL);
INSERT INTO salaries (birth_year, salary) VALUES
('1946-01-01',78000), ('1949-01-01',61000), ('1951-01-01',58000)
, ('1953-01-01',56000), ('1958-01-01',52000), ('1962-01-01',50000)
, ('1965-01-01',45000), ('1967-01-01',60000), ('1968-01-01',57000)
, ('1970-01-01',47000), ('1972-01-01',32000), ('1973-01-01',42000);
SELECT birth_decade, AVG(salary)
FROM (
SELECT birth_year
, date_trunc('decade', birth_year)::date as birth_decade
, salary
FROM salaries) as salaries_with_decades
GROUP BY birth_decade
ORDER BY birth_decade;
birth_decade | avg
--------------+--------------------
1940-01-01 | 69500.000000000000
1950-01-01 | 55333.333333333333
1960-01-01 | 53000.000000000000
1970-01-01 | 40333.333333333333
(4 rows)
If birth_year is an integer column, here's another way to do it,
taking advantage of the fact that integer division truncates.
CREATE TABLE salaries (birth_year INTEGER PRIMARY KEY, salary NUMERIC
NOT NULL);
INSERT INTO salaries (birth_year, salary) VALUES
(1946,78000), (1949,61000), (1951,58000), (1953,56000),
(1958,52000)
, (1962,50000), (1965,45000), (1967,60000), (1968,57000),
(1970,47000)
, (1972,32000), (1973,42000);
SELECT birth_decade, AVG(salary)
FROM (
SELECT birth_year
, birth_year / 10 * 10 as birth_decade
, salary
FROM salaries) as salaries_with_decades
GROUP BY birth_decade
ORDER BY birth_decade;
birth_decade | avg
--------------+--------------------
1940 | 69500.000000000000
1950 | 55333.333333333333
1960 | 53000.000000000000
1970 | 40333.333333333333
(4 rows)
Hope this gives you some options.
Michael Glaesemann
grzm seespotcode net
^ permalink raw reply [nested|flat] 6+ messages in thread
end of thread, other threads:[~2007-07-27 20:43 UTC | newest]
Thread overview: 6+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2007-07-27 19:05 group by range of values Carol Cheung <cacheung@consumercontact.com>
2007-07-27 19:25 ` Jon Sime <jsime@mediamatters.org>
2007-07-27 19:28 ` Rodrigo De León <rdeleonp@gmail.com>
2007-07-27 19:31 ` Rodrigo De León <rdeleonp@gmail.com>
2007-07-27 19:30 ` Pavel Stehule <pavel.stehule@gmail.com>
2007-07-27 20:43 ` Michael Glaesemann <grzm@seespotcode.net>
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