我有一个关于主键或复合键的问题。我创建了一个表,其中只有两个属性,并且都是主键。
主键名称是item_ID̀ and
SName`
这两个是另一个主键(其他两个表)的外键,其中:
item_ID --> ID
和SName --> SkillName
项目 ID 名称 1 基本武器 2 3 4 重型武器 5 种异国武器 6 重型武器 7 动力武器
结果是这样的:
ID nr 2 和 3 不需要技能名称要求。出于这个原因,我已经这样实现了(因为主键不允许为空):
INSERT INTO Requierments (item_ID, SName) VALUES (
01, 'Basic weapons');
INSERT INTO Requierments (item_ID, SName) VALUES (
02, null);
INSERT INTO Requierments (item_ID, SName) VALUES (
03, null);
INSERT INTO Requierments (item_ID, SName) VALUES (
04, 'Heavy weapon');
INSERT INTO Requierments (item_ID, SName) VALUES (
05, 'Exotic Weapons');
INSERT INTO Requierments (item_ID, SName) VALUES (
06, 'Heavy weapon');
INSERT INTO Requierments (item_ID, SName) VALUES (
07, 'Power weapon');
这样做正确吗?或者是否有另一种方式来编码 ID 不需要特定的 SName?
这是 3 个表的代码:
CREATE TABLE `talents` (
`SkillName` varchar(30) NOT NULL DEFAULT '',
`Bonus` varchar(30) DEFAULT NULL,
`Description` varchar(70) DEFAULT NULL,
`R_Str` int(11) DEFAULT NULL,
`R_WS` int(11) DEFAULT NULL,
`R_BS` int(11) DEFAULT NULL,
`R_Fel` int(11) DEFAULT NULL,
`R_Per` int(11) DEFAULT NULL,
`R_Int` int(11) DEFAULT NULL,
`R_Agi` int(11) DEFAULT NULL,
`R_WP` int(11) DEFAULT NULL,
`Talent_requiert` varchar(30) DEFAULT NULL,
PRIMARY KEY (`SkillName`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `requierments` (
`item_ID` int(11) NOT NULL DEFAULT '0',
`SName` varchar(30) NOT NULL DEFAULT '',
PRIMARY KEY (`item_ID`,`SName`),
CONSTRAINT `requierments_ibfk_1` FOREIGN KEY (`item_ID`) REFERENCES `item` (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `item` (
`ID` int(11) NOT NULL DEFAULT '0',
`Name_` varchar(30) DEFAULT NULL,
`Weight` int(11) DEFAULT NULL,
`Value_` int(11) DEFAULT NULL,
`Availability` varchar(30) DEFAULT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
这个想法是在表需求 item_ID ---> 项目表中的 ID 和 SName ---> 天赋中的技能名。出于某种原因,我能够从 item_ID 到 ID 制作外键,但不能从 SName 到 SkillName:
我添加到这些表中的值如下(OBS 在表要求中我已将 ID 2 和 3 设置为 '' 因为不需要任何人才就可以选择它。但我不确定我是否被允许用那个方法?
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'ambidextrous', 0, 'use either hand equally well', 0, 0, 0, 0, 0, 0, 30, 0, null);
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'Frenzy', 0, 'enter psychotic rage to gain combat bonus', 0, 0, 0, 0, 0, 0, 0, 0, null);
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'battle rage', 0, 'parry while frenzied', 0, 0, 0, 0, 0, 0, 0, 0, 'Frenzy');
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'Exotic Weapons', 0, 'Player is able to use exotic weapons', 0, 0, 0, 0, 0, 0, 0, 0, 'Basic weapons');
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'Basic weapons', 0, 'Player is able to use Basic weapons', 0, 0, 0, 0, 0, 0, 0, 0, null);
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'Heavy weapon', 0, 'Player is able to use heavy weapons', 30, 0, 0, 0, 0, 0, 0, 0, null);
INSERT INTO Talents ( SkillName, Bonus, Description, R_Str, R_WS, R_BS, R_Fel, R_Per, R_Int, R_Agi, R_WP, Talent_requiert) VALUES (
'Power weapon', 0, 'Player is able to use power weapons ', 40, 30, 0, 0, 0, 0, 0, 0, null);
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
01, 'Las Carbine', 3, 75, 'Common' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
02, 'Laspistol', 1, 50, 'Common' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
03, 'Shotgun', 5, 60, 'average' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
04, 'Heavy Bolter', 40, 2000, 'Very Rare' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
05, 'Needle pistol', 2, 1250, 'Very Rare' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
06, 'Chainsword', 6, 275, 'Rare' );
INSERT INTO Item ( ID, Name_, Weight, Value_, Availability) VALUES (
07, 'Power Sword', 4, 2500, 'Very Rare' );
INSERT INTO Requierments (item_ID, SName) VALUES (
01, 'Basic weapons');
INSERT INTO Requierments (item_ID, SName) VALUES (
02, '');
INSERT INTO Requierments (item_ID, SName) VALUES (
03, '');
INSERT INTO Requierments (item_ID, SName) VALUES (
04, 'Heavy weapon');
INSERT INTO Requierments (item_ID, SName) VALUES (
05, 'Exotic Weapons');
INSERT INTO Requierments (item_ID, SName) VALUES (
06, 'Heavy weapon');
INSERT INTO Requierments (item_ID, SName) VALUES (
07, 'Power weapon');