Thank's for your reply. I didnt realize this, but of course it is logical.
So, now I think how to select not only one row (what seems to be easy) but
set of rows from previously mentioned data where only these rows are
picked up with largest Data value for each IdMat, so correct version of
querry:
SELECT Mieszalnia.IdMat, Mieszalnia.Partia, Mieszalnia.Kont,
Mieszalnia.Uk, Max(Mieszalnia.Data) FROM Mieszalnia GROUPED BY
Mieszalnia.IdMat;
IdW IdMat Partia Kont Uk Data
12 1 1179760 136832 F16 1171951258
12 2 1176865 315060 F21 1171915832
13 3 1177504 318272 F9 1171538132
15 4 1153571 277827 F15 1171437632
16 5 1153437 062022 F16 1171368032
17 6 1185543 323063 SL1 1171978232
18 7 1156166 077690 F3 1169082032
19 8 1156269 075825 F8 1168888832
20 9 1166581 101109 F11 1168014032
21 10 1099211 081868 F17 1166497232
22 11 1084774 054445 F20 1169530232
23 12 1143641 157155 F24 1171485032
24 13 1180275 179329 SF3 1169521232
25 14 1102698 150010 SF4 1171494000
26 15 1130267 266647 SF5 1170282600
27 6 111111 111111 sl1 1172135769
28 6 33333 33333 sl1 1172054927
woj <[EMAIL PROTECTED]> wrote:
Now, when I run a query:
SELECT Mieszalnia.IdMat, Mieszalnia.Partia, Mieszalnia.Kont,
Mieszalnia.Uk, Max(Mieszalnia.Data) FROM Mieszalnia;
I always get:
IdMat Partia Kont Uk Data
6 33333 33333 sl1 1172135769
In this result there is indeed max from Data field but rest of the
fields fit not...
When a SELECT statement involves aggregate functions, all column
references in the SELECT must be either parameters to some aggregate
functions, or else be also mentioned in GROUP BY clause. SQLite allows,
as an extension, departure from this rule, but the row from which values
for columns that are neither aggregated nor grouped by are taken is
random and unpredictable.
Specifically, in the query you show, there's no guarantee that values
for IdMat, Partia and so on would be taken from the same row from which
Max(Data) comes. Even if SQLite really wanted to help you out here, it
is impossible in general. Consider:
SELECT IdMat, Max(Data), Min(Data) from Mieszalnia;
Which value of IdMat would you expect to see in response to such a
query? Should it come from the row with the largest value of Data, with
the smallest, or some other?
There are many ways to formulate the query you seem to want. E.g.
select IdMat, Data from Mieszalnia
order by Data desc limit 1;
select IdMat, Data from Mieszalnia
where Data = (select max(Data) from Mieszalnia);
Igor Tandetnik
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