MySQL语法错误1064行194添加多对多关系的外键

Question

请帮助我。我收到以下消息时，我尝试运行SQL命令：

 
ERROR 1064 (42000) at line 194: 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 '(
    ADD CONSTRAINT VFSGRPUSR_REF_VFSGRP 
     FOREIGN KEY (VFSGRP) 
     REFERENCES `VFS' at line 1 

我想实现一个多到多的关系。

 

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DROP TABLE IF EXISTS VFSGRPUSR;
 

CREATE TABLE VFSGRPUSR ( VFSGRP INTEGER REFERENCES VFSGRP(VFSGRP_ID), VFSUSR INTEGER REFERENCES VFSUSR(VFSUSR_ID), PRIMARY KEY (VFSGRP, VFSUSR) )ENGINE=InnoDB DEFAULT CHARSET utf8;
 

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DROP TABLE IF EXISTS VFSUSR;
 

CREATE TABLE VFSUSR ( VFSUSR_ID INTEGER NOT NULL auto_increment, DEPARTMENT INTEGER, FIRSTNAME VARCHAR(255) NOT NULL, SURNAME VARCHAR(255) NOT NULL, LOGIN VARCHAR(255) NOT NULL, PASSWORD BLOB, TOKEN BLOB, PRIMARY KEY (VFSUSR_ID), CONSTRAINT VFSUSR_REF_DEPARTMENT FOREIGN KEY (DEPARTMENT) REFERENCES DEPARTMENT (DEPARTMENT_ID) )ENGINE=InnoDB DEFAULT CHARSET utf8;
 

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DROP TABLE IF EXISTS VFSGRP;
 

CREATE TABLE VFSGRP ( VFSGRP_ID INTEGER NOT NULL auto_increment, GROUPNAME VARCHAR(255) NOT NULL, PRIMARY KEY (VFSGRP_ID) )ENGINE=InnoDB DEFAULT CHARSET utf8;
 

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ALTER TABLE VFSGRPUSR( ADD CONSTRAINT VFSGRPUSR_REF_VFSGRP FOREIGN KEY (VFSGRP) REFERENCES VFSGRP(VFSGRP_ID) )ENGINE=InnoDB DEFAULT CHARSET utf8;
 

ALTER TABLE VFSGRPUSR( ADD CONSTRAINT VFSGRPUSR_REF_VFSUSR FOREIGN KEY (VFSUSR) REFERENCES VFSUSR(VFSUSR_ID) )ENGINE=InnoDB DEFAULT CHARSET utf8; 

Answer 1

为什么你想也设置ENGINE和CHARSET？只需使用：

ALTER TABLE VFSGRPUSR 
    ADD CONSTRAINT VFSGRPUSR_REF_VFSGRP 
     FOREIGN KEY (VFSGRP) 
     REFERENCES VFSGRP(VFSGRP_ID); 

，并参考官方文档可用的语法：http://dev.mysql.com/doc/refman/5.1/en/alter-table.html