在mysql中创建关联实体

我试图通过关联实体LINEITEM组合这两个表，当我试图在代码中设置主键和外键时，它总是给我错误。任何帮助都将不胜感激。谢谢

Database changed mysql> select * from STUDENT; +---------+--------+-----+ | SFName | SLName | SID | +---------+--------+-----+ | Geno | Smith | 1 | | Kevin | White | 2 | | Tavon | Austin | 3 | | Charles | Sims | 4 | | Mario | Alford | 5 | +---------+--------+-----+ 5 rows in set (0.00 sec) mysql> select * from ASSIGNMENT; +------------------+-------+ | AName | AType | +------------------+-------+ | Final Exam | T | | Formal Report | H | | Grammar Exercise | H | | Informal Report | H | | Midterm | T | | Resume | H | +------------------+-------+ 6 rows in set (0.00 sec)

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mysql>

VARCHAR需要一个长度。请看，如果您提供错误消息会有所帮助。这很有效，我感谢您的帮助！

create table LINEITEM
( SID int
, AName varchar
, LIGrade decimal(5,2)
, primary key(SID, AName)
, foreign key (SID) references STUDENT(SID)
, foreign key (AName) references ASSIGNMENT(AName)
);
ERROR 1064 (42000): You have an error in your SQL syntax; 
check the manual that corresponds to your MySQL server version for the right syntax to use near 
' LIGrade decimal(5,2), primary key(SID, AName), foreign key (SID) references STU' at line 1