我有四个表，其中三个需要我的数据，还有第四个存储该数据如何关联的表。运行查询时，我得到的输出是错误的，似乎我没有正确地链接起来，但是我不确定该怎么做。如何链接我的联接以获取所需的输出？
到目前为止，我已经使用过
SELECT c.class, p.name, s.specialization
FROM players_classes pc
JOIN players p ON p.player_id=pc.player_id
JOIN classes c ON c.class_id=pc.class_id
JOIN specialization s ON s.spec_id=pc.spec_id
引用
CREATE TABLE players(
player_id INT UNSIGNED auto_increment PRIMARY KEY,
name VARCHAR(20)
)...;
CREATE TABLE classes(
class_id INT UNSIGNED auto_increment PRIMARY KEY,
class VARCHAR(20)
)...;
CREATE TABLE specializations(
spec_id INT UNSIGNED auto_increment PRIMARY KEY,
class_id INT UNSIGNED,
specialization VARCHAR(20)
)...;
但是我想以某种方式使用此表来显示正确链接的信息，但我不确定如何做到：
CREATE TABLE players_classes(
pc_id INT UNSIGNED auto_increment PRIMARY KEY,
FOREIGN KEY(class_id) REFERENCES classes(class_id),
FOREIGN KEY(player_id) REFERENCES players(player_id),
FOREIGN KEY(spec_id) REFERENCES specializations(spec_id)
)...;
我希望能够获得玩家的名字以及他们相关的职业和专长，实际结果是显示每个ID与1/1/1相关的值，依此类推。
编辑：players_classes中的数据如下
pc_id | class_id | player_id | spec_id |
1 3 1 8
2 12 2 35
3 2 3 6
etc.
因此，预期结果是
class | name | spec
paladin seranul holypa
hunter contherious marksmanship
priest unicorns holypr
我反而得到
class | name | spec
warlock Affliction Affliction
warlock Grireaver Demonology
warlock Affliction Demonology
依此类推，列出了我的players_classes表中不存在的组合
专业化表
+---------+----------+----------------+
| spec_id | class_id | specialization |
+---------+----------+----------------+
| 1 | 1 | Affliction |
| 2 | 1 | Destruction |
| 3 | 1 | Demonology |
| 4 | 2 | Shadow |
| 5 | 2 | Discipline |
| 6 | 2 | HolyPr |
| 7 | 3 | Retribution |
| 8 | 3 | HolyPa |
| 9 | 3 | ProtectionPa |
| 10 | 4 | ProtectionWa |
| 11 | 4 | Arms |
| 12 | 4 | Fury |
| 13 | 5 | FrostMa |
| 14 | 5 | Fire |
| 15 | 5 | Arcane |
| 16 | 6 | vengeance |
| 17 | 6 | havoc |
| 18 | 7 | guardian |
| 19 | 7 | balance |
| 20 | 7 | feral |
| 21 | 7 | restorationDr |
| 22 | 8 | elemental |
| 23 | 8 | enhance |
| 24 | 8 | restorationSh |
| 25 | 9 | frostDk |
| 26 | 9 | blood |
| 27 | 9 | unholy |
| 28 | 10 | outlaw |
| 29 | 10 | assassin |
| 30 | 10 | subtlety |
| 31 | 11 | brewmaster |
| 32 | 11 | windwalker |
| 33 | 11 | mistweaver |
| 34 | 12 | BeastMaster |
| 35 | 12 | marksmanship |
| 36 | 12 | Survival |
+---------+----------+----------------+
课程表
+----------+-------------+
| class_id | class |
+----------+-------------+
| 1 | warlock |
| 2 | priest |
| 3 | paladin |
| 4 | warrior |
| 5 | mage |
| 6 | demonhunter |
| 7 | druid |
| 8 | shaman |
| 9 | deathknight |
| 10 | rogue |
| 11 | monk |
| 12 | hunter |
+----------+-------------+
玩家表
+-----------+--------------+
| player_id | name |
+-----------+--------------+
| 1 | Seranul |
| 2 | Contherious |
| 3 | Unicorns |
| 4 | Remereili |
| 5 | Affliction |
| 6 | Meowing |
| 7 | Brobot |
| 8 | Bagelsbbq |
| 9 | Rafusen |
| 10 | Taiboku |
| 11 | Yikes |
| 12 | Thunderblaze |
| 13 | Muo |
| 14 | Intz |
| 15 | Trunks |
| 16 | Kalphyte |
| 17 | Eyeoftheshoe |
| 18 | Amuhnet |
| 19 | Synkka |
| 20 | Affliction |
| 21 | Kts |
| 22 | Shadowdreams |
| 23 | Zahel |
| 24 | Azrama |
| 25 | Seranul |
| 26 | Momspaghetti |
| 27 | Ohki |
| 28 | Rafusen |
| 29 | Cindyy |
| 30 | Grireaver |
| 31 | Intz |
| 32 | lazy |
| 33 | missworld |
| 34 | Affliction |
| 35 | Amuhnet |
| 36 | eyeoftheshoe |
| 37 | sanctus |
| 38 | nozshelen |
| 39 | Contherious |
| 40 | messer |
| 41 | catathor |
| 42 | demonblaze |
| 43 | wrillett |
| 44 | raagnnar |
| 45 | xizi |
| 46 | nemesix |
| 47 | zeroskill |
| 48 | chikfillidan |
| 49 | tentenlol |
| 50 | unicorns |
| 51 | bubuhtide |
| 52 | ohki |
| 53 | azrama |
+-----------+--------------+
players_classes表
+-------+----------+-----------+---------+
| pc_id | class_id | player_id | spec_id |
+-------+----------+-----------+---------+
| 1 | 3 | 1 | 8 |
| 2 | 12 | 2 | 35 |
| 3 | 2 | 3 | 6 |
| 4 | 11 | 4 | 31 |
| 5 | 1 | 5 | 1 |
| 6 | 12 | 6 | 34 |
| 7 | 2 | 7 | 6 |
| 8 | 11 | 8 | 31 |
| 9 | 2 | 9 | 6 |
| 10 | 7 | 10 | 21 |
| 11 | 4 | 11 | 11 |
| 12 | 8 | 12 | 22 |
| 13 | 4 | 13 | 12 |
| 14 | 5 | 14 | 13 |
| 15 | 3 | 15 | 7 |
| 16 | 11 | 16 | 33 |
| 17 | 8 | 17 | 22 |
| 18 | 2 | 18 | 6 |
| 19 | 8 | 19 | 23 |
| 20 | 11 | 20 | 33 |
| 21 | 5 | 21 | 13 |
| 22 | 6 | 22 | 17 |
| 23 | 10 | 23 | 29 |
| 24 | 8 | 24 | 22 |
| 25 | 11 | 25 | 31 |
| 26 | 11 | 26 | 32 |
| 27 | 4 | 27 | 11 |
| 28 | 5 | 28 | 13 |
| 29 | 7 | 29 | 19 |
| 30 | 1 | 30 | 3 |
| 31 | 9 | 31 | 25 |
| 32 | 3 | 32 | 8 |
| 33 | 9 | 33 | 25 |
| 34 | 1 | 34 | 3 |
| 35 | 2 | 35 | 6 |
| 36 | 4 | 36 | 11 |
| 37 | 5 | 37 | 13 |
| 38 | 5 | 38 | 13 |
| 39 | 9 | 39 | 25 |
| 40 | 6 | 40 | 17 |
| 41 | 10 | 41 | 28 |
| 42 | 2 | 42 | 6 |
| 43 | 8 | 43 | 24 |
+-------+----------+-----------+---------+
答案 0 :(得分：1)
您需要在查询中使用关系表：
SELECT c.class, p.name, s.specialization
FROM players_classes pc
JOIN players p ON p.player_id = pc.player_id
JOIN classes c ON c.class_id = pc.class_id
JOIN specializations s ON s.spec_id = pc.spec_id
在其他表中甚至不应该包含class_id和spec_id，因为它们是多对多关系，并且这些列只能用于一对一关系。