Обсуждение: MAX, MIN and arrays

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MAX, MIN and arrays

От
Colton A Smith
Дата:
Hi:
  Let's say I have a table with a column of one-dimensional arrays.  What 
exactly is returned when the database is queried for a maximum from that 
particular column?  The array was the greatest average value?  Let's say
I have a table with a column of two-dimensional arrays.  What then?

Thanks!


Re: MAX, MIN and arrays

От
Andreas Kretschmer
Дата:
Colton A Smith <smith@cs.utk.edu> schrieb:

> Hi:
> 
>    Let's say I have a table with a column of one-dimensional arrays.  What 
> exactly is returned when the database is queried for a maximum from that 
> particular column?  The array was the greatest average value?  Let's say

What du you expect?

test=# select * from foo;id |   bar
----+--------- 1 | {1,2,3} 2 | {2,2,2} 3 | {3,2,1}
(3 rows)

Which row is the max()?


test=# select max(bar) from foo;  max
---------{3,2,1}
(1 row)


It compares the first value in every array. If you wish to compare the
array depending on a other column, you can use somethink like

test=# select id, bar from foo order by bar ;id |   bar
----+--------- 1 | {1,2,3} 2 | {2,2,2} 3 | {3,2,1}
(3 rows)

test=# select id, bar from foo order by bar[3] ;id |   bar
----+--------- 3 | {3,2,1} 2 | {2,2,2} 1 | {1,2,3}
(3 rows)




> I have a table with a column of two-dimensional arrays.  What then?

The same.


HTH, Andreas
-- 
Really, I'm not out to destroy Microsoft. That will just be a completely
unintentional side effect. (Linus Torvalds)
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