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我试图获得以下行为:Mysql的提高选择结表查询
+-----+--------------+-----+-----+-----+-------+-------+-------+--------+--------+
| id | name | hp | atk | def | spatk | spdef | speed | type1 | type2 |
+-----+--------------+-----+-----+-----+-------+-------+-------+--------+--------+
| 1 | Bulbasaur | 45 | 49 | 49 | 65 | 65 | 45 | GRASS | POISON |
| 2 | Ivysaur | 60 | 62 | 63 | 80 | 80 | 60 | GRASS | POISON |
| 3 | Venusaur | 80 | 82 | 83 | 100 | 100 | 80 | GRASS | POISON |
+-----+--------------+-----+-----+-----+-------+-------+-------+--------+--------+
凡3代表的定义如下:
pokedex:
+----+------------+----+-----+-----+-------+-------+-------+
| id | name | hp | atk | def | spatk | spdef | speed |
+----+------------+----+-----+-----+-------+-------+-------+
| 1 | Bulbasaur | 45 | 49 | 49 | 65 | 65 | 45 |
| 2 | Ivysaur | 60 | 62 | 63 | 80 | 80 | 60 |
| 3 | Venusaur | 80 | 82 | 83 | 100 | 100 | 80 |
+----+------------+----+-----+-----+-------+-------+-------+
poke_type:
+------------+---------+
| pokedex_id | type_id |
+------------+---------+
| 1 | 13 |
| 1 | 5 |
| 2 | 13 |
| 2 | 5 |
+------------+---------+
type:
+----+----------+
| id | name |
+----+----------+
| 1 | NONE |
| 5 | POISON |
| 13 | GRASS |
+----+----------+
据了解,每个pokedex
项关联与2 type
在poke_type
表中。我试图做一个查询,如:
USE pokemon;
SELECT dex.*,
t1.name AS type1,
t2.name AS type2
FROM pokedex AS dex,
(SELECT pt.pokedex_id AS dexid, t.name AS name
FROM pokedex AS d
INNER JOIN poke_type AS pt ON d.id = pt.pokedex_id
INNER JOIN type as t ON pt.type_id = t.id
) AS t1,
(SELECT pt.pokedex_id AS dexid, t.name AS name
FROM pokedex AS d
INNER JOIN poke_type AS pt ON d.id = pt.pokedex_id
INNER JOIN type as t ON pt.type_id = t.id
) AS t2
WHERE dex.id = t1.dexid AND dex.id = t2.dexid AND t1.name <> t2.name
GROUP BY dex.id -- remove duplicates
这是一个丑陋的查询,可能不是真的有效。任何想法如何改进这个查询/选择以不同的方式?