Mysql外键用法是Mysql数据库中的基础知识，下面就为您详细将介绍Mysql外键用法，如果您对此方面有兴趣的话，不妨一看。

昨晚用Mysql建外键约束，始终没有成功，今天找到这个，原来只有InnoDB类型的表才可以使用Mysql外键.

只有InnoDB类型的表才可以使用外键

CREATETABLEperson( 
idSMALLINTUNSIGNEDNOTNULLAUTO_INCREMENT, 
nameCHAR(60)NOTNULL, 
PRIMARYKEY(id) 
)type=innoDB; 

CREATETABLEshirt( 
idSMALLINTUNSIGNEDNOTNULLAUTO_INCREMENT, 
styleENUM('t-shirt','polo','dress')NOTNULL, 
colorENUM('red','blue','orange','white','black')NOTNULL, 
ownerSMALLINTUNSIGNEDNOTNULL, 
FOREIGNKEY(owner)REFERENCESPERSON(id) 
ONDELETECASCADE 
ONUPDATECASCADE, 
PRIMARYKEY(id) 
)type=innoDB; 

然后打开MySQL Administrator终于看到 FOREIGN KEY有东西了，尝试手工删除后再用MySQL Administrator建立，成功。

INSERTINTOpersonVALUES(NULL,'AntonioPaz'); 

SELECT@last:=LAST_INSERT_ID(); 

INSERTINTOshirtVALUES 
(NULL,'polo','blue',@last), 
(NULL,'dress','white',@last), 
(NULL,'t-shirt','blue',@last); 

INSERTINTOpersonVALUES(NULL,'LillianaAngelovska'); 

SELECT@last:=LAST_INSERT_ID(); 

INSERTINTOshirtVALUES 
(NULL,'dress','orange',@last), 
(NULL,'polo','red',@last), 
(NULL,'dress','blue',@last), 
(NULL,'t-shirt','white',@last); 

SELECT*FROMperson; 

SELECT*FROMshirt; 

测试UPDATE关联

UPDATEPERSONSETid=3WHEREid=1; 
SELECT*FROMshirt; 

测试DELETE关键

DELETEFROMPERSONWHEREid=3; 
SELECT*FROMshirt;