Nezgodan upit

[Pedja]

Imam jedan problem ali nikako da ga namikarim.

Imam tabelu:

t1 (id, value, desc)

Value je unique, dakle ne mogu biti dva sloga sa istim value.


Iz ove treba da napravim:

t2 (id, value_min, value_max, desc_for_min, desc_for_max)

Dosao sam do:

SELECT 
  id, 
  MIN(value) as value_min, 
  MAX(value) as value_max, 
FROM t1
GROUP BY id
ORDER BY id

Sto je jednostavno ... ali nikako da mi sevne kako da prosirim upit da dodam i polja desc_for_min i desc_for_max gde ova dva polja predstavljaju vrednost desc za logove u t1 koji imaju za value vrednosti value_min i value_max.

Znam kako da resim sa dva SELECT-a ali bih ja hteo jednim

Hitno je ljudi...

[noviKorisnik]

Joj kako me zbunjuješ - id ti je strani ključ u T1, zar ne? A primarni ključ je u stvari value. Inače nema smisla da tražiš minimume i maksimume od value po id. ...

Trebalo bi da može sa subselektima da se to odradi, ali sam prilično zarđao po tom pitanju ;-) - glupo mi je da lupam sad ... ali verovatno hoću :-D

[zextra]

... ja kazem:

mysql> select 'asdf';

+------+

| asdf |

+------+

| asdf |

+------+

1 row in set (0.00 sec)



mysql> select 'asdf' as desc1;

+-------+

| desc1 |

+-------+

| asdf   |

+-------+

1 row in set (0.01 sec)

Jel bi sad znao?

Da kompletiram resenje:

INSERT `t2` (id, value_min, value_max, desc_for_min, desc_for_max)
SELECT 
  id,
  MIN(value) as value_min,
  MAX(value) as value_max,
  'description min' as desc_for_min,
  'description max' as desc_for_max
FROM t1
GROUP BY id
ORDER BY id

U datom slucaju ti ne trebaju "as col_name" dodaci, posto je samo bitno da se poklopi broj kolona.

[edit]Napomena: gornji kod je sve jedan query, da se neko ne zbuni [/edit]

[Pedja]

Originalno napisao noviKorisnik

Joj kako me zbunjuješ - id ti je strani ključ u T1, zar ne? A primarni ključ je u stvari value. Inače nema smisla da tražiš minimume i maksimume od value po id. ...

Da, bas tako.

Originalno napisao zextra

'description min' as desc_for_min,
'description max' as desc_for_max

Xe xe, dobra sala

Evo kako sam resio stvar sa pomocnom tabelom:

CREATE TABLE tempdata
SELECT
id,
MIN(value) as value_min,
MAX(value) as value_max,
FROM t1
GROUP BY id
ORDER BY id

SELECT
t.id,
t.value_min,
t.value_max,
tmin.desc as desc_for_min,
tmax.desc as desc_for_max
FROM tempdata t
LEFT JOIN t1 as tmin ON t.id = tmin.id
LEFT JOIN t1 as tmax ON t.id = tmax.id

DROP TABLE tempdata

[zextra]

[edit]Eve ga.. Prethodno sam mislio da hoces proizvoljan komentar za min i max vrednosti, lol [/edit]

mysql> select * from t1 order by id, value;

+------+-------+-------+

| id   | value | descr |

+------+-------+-------+

|    1 |     8 | var 8 |

|    1 |    24 | var 2 |

|    1 |    97 | var 4 |

|    2 |    12 | var 1 |

|    2 |    73 | var 7 |

|    2 |   102 | var 5 |

+------+-------+-------+

6 rows in set (0.02 sec)



mysql> select q1.id, q1.min, q2.max, s1.descr as 'd_min', s2.descr as 'd_max' from t1 s1, t1 s2, (select id, min(value) as 'min' from t1 group by id order by id) q1, (select id, max(value) as 'max' from t1 group by id order by id) q2 where s1.value=q1.min and s2.value=q2.max and q1.id=q2.id;

+------+------+------+-------+-------+

| id   | min  | max  | d_min | d_max |

+------+------+------+-------+-------+

|    1 |    8 |   97 | var 8 | var 4 |

|    2 |   12 |  102 | var 1 | var 5 |

+------+------+------+-------+-------+

2 rows in set (0.00 sec)

SELECT
  q1.id AS 'id',
  q1.min AS 'value_min',
  q2.max AS 'value_max',
  s1.descr AS 'desc_for_min',
  s2.descr AS 'desc_for_max'
FROM
  `t1` s1,
  `t1` s2,
  ( SELECT id, min(value) AS 'min' FROM `t1` GROUP BY id ORDER BY id ) q1,
  ( SELECT id, max(value) AS 'max' FROM `t1` GROUP BY id ORDER BY id ) q2
WHERE
      s1.value = q1.min
  AND s2.value = q2.max
  AND q1.id = q2.id

[zextra]

Off Topic: postovano greskom, moze li remove?

[bluesman]

Ja mislim da je ovde "skuplja dara nego mera" (ili kako vec bese... )

2 simple querija bi zavrsila posao jednostavnije nego sve predlozeno.

[zextra]

Moze li primer?

[Pedja]

Originalno napisao zextra

...
FROM
  `t1` s1,
  `t1` s2,
  ( SELECT id, min(value) AS 'min' FROM `t1` GROUP BY id ORDER BY id ) q1,
  ( SELECT id, max(value) AS 'max' FROM `t1` GROUP BY id ORDER BY id ) q2
WHERE
...

Ovo moram da probam. Nikad mi ne bi palo na pamet da ovde uglavim SELECT. Ja sam probavao da slicno uradim u LEFT JOIN ali nije proslo posto funkcije ne rade u LEFT JOIN uslovu.

[Dejan Topalovic]

@Pedja: Ono rjesenje sa temp tabelom ce ti biti dosta sporije, nego da radis sa subselectima... Izbjegavaj to kad god mozes...

Inace, pokusao sam i ja da sklepam odgovarajuci upit, ali sam dosao do slicnog rjesenja kao zextra:

select t1.id, t2.id, t1.value, t2.value, t1.description, t2.description
  from test_dejan t1, test_dejan t2, 
   (select min(value) min_value, max(value) max_value from test_dejan group by id) sub
  where t1.id = t2.id
    and t1.value = sub.min_value
	and t2.value = sub.max_value

Ne znam da li mogu da kopiram ovdje output od explain plan komande, a da se tekst ispravno prikaze... ? Ja cu kopirati, a nek neko od moderatora doda odgovarajuce tagove za formatiranje teksta..

Prvo je izlistan rezultat moga upita, a potom rezultat upita, kojeg je postavio zextra.

  Operation	  	   	   	  	 	 	  Object Name	Rows	Bytes	Cost	Object Node	In/Out	PStart	PStop

SELECT STATEMENT Optimizer Mode=ALL_ROWS			1  	 	    	11.0246977930899  	 	      	             	 
  HASH JOIN		 		   							1  		114  	11.0246977930899  	 	      	             	 
    HASH JOIN										1  		70  	7.51653332072425  	 	      	             	 
      TABLE ACCESS FULL	ONOPER.TEST_DEJAN			7  		308  	3.00797875329891  	 	      	             	 
      VIEW		   									7  		182  	4.00817220464087  	 	      	             	 
        SORT GROUP BY								7  		182  	4.00817220464087  	 	      	             	 
          TABLE ACCESS FULL	ONOPER.TEST_DEJAN		7  		182  	3.00797875329891  	 	      	             	 
    TABLE ACCESS FULL	ONOPER.TEST_DEJAN			7  		308  	3.00797875329891  	 	      	             	 

	
	
	Operation	 					  Object Name	Rows	Bytes	Cost	Object Node	In/Out	PStart	PStop

SELECT STATEMENT Optimizer Mode=ALL_ROWS			7  	 			15.533449004233  	 	      	             	 
  HASH JOIN		 		   							7  		798  	15.533449004233  	 	      	             	 
    HASH JOIN										7  		581  	12.0250878881496  	 	      	             	 
      HASH JOIN										7  		399  	7.51653332072425  	 	      	             	 
        TABLE ACCESS FULL	ONOPER.TEST_DEJAN		7  		217  	3.00797875329891  	 	      	             	 
        VIEW		 								7  		182  	4.00817220464087  	 	      	             	 
          SORT GROUP BY								7  		182  	4.00817220464087  	 	      	             	 
            TABLE ACCESS FULL	ONOPER.TEST_DEJAN	7  		182  	3.00797875329891  	 	      	             	 
      VIEW		  		 							7  		182  	4.00817220464087  	 	      	             	 
        SORT GROUP BY								7  		182  	4.00817220464087  	 	      	             	 
          TABLE ACCESS FULL	ONOPER.TEST_DEJAN		7  		182  	3.00797875329891  	 	      	             	 
    TABLE ACCESS FULL	ONOPER.TEST_DEJAN			7  		217  	3.00797875329891