Question

//从MySQL导出表

CREATE TABLE `pairs` (
  `parent` varchar(12) NOT NULL,
  `child` varchar(12) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE `pairs` ADD PRIMARY KEY (`parent`,`child`);

/ ---------------------------------------------- -------------------------------------------------- ----------------

//从MySQL导出表

CREATE TABLE `dailyreports` (
  `SquareNo` varchar(5) NOT NULL,
  `id` varchar(12) NOT NULL,
  `notes` longtext,
  `dateReport` date DEFAULT NULL,
  `signed1` varchar(20) DEFAULT NULL,
  `signed2` varchar(20) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DELIMITER $$
CREATE TRIGGER `dailyreport_BEFORE_INSERT` BEFORE INSERT ON `dailyreports` FOR EACH ROW BEGIN
    declare SqNo varchar(5);
    declare CUser varchar(12);
    declare serNo INT;
    Set SqNo = new.SquareNo;
    Set CUser = new.id;
    Select Serial Into serNo from squareserials where Category ='DR' and SquareNo = SqNo;
    SET NEW.id = CONCAT(SqNo,'-DR',SUBSTRING('0000',1,4-LENGTH(CAST(serNo AS CHAR))),CAST(serNo AS CHAR));
    update squareserials set Serial = Serial +1 where Category ='DR' and SquareNo = SqNo;
    insert into activities (username,activity) values (CUser,CONCAT('Added Daily Report ',NEW.id));
END
$$
DELIMITER ;

ALTER TABLE `dailyreports` ADD PRIMARY KEY (`SquareNo`,`id`);
ALTER TABLE `dailyreports` ADD CONSTRAINT `FK_DR_SquareNo` FOREIGN KEY (`SquareNo`) REFERENCES `squareserials` (`SquareNo`) ON UPDATE CASCADE;

/ ---------------------------------------------- -------------------------------------------------- ----------------

以下语句不起作用，给出错误“＃1215 - 无法添加外键约束”

ALTER TABLE pairs ADD CONSTRAINT FK_DR_Parent FOREIGN KEY (parent) REFERENCES dailyreports(id) ON UPDATE CASCADE ON DELETE RESTRICT;

任何想法都将不胜感激。

Answer 1

问题在于：

ALTER TABLE pairs ADD CONSTRAINT FK_DR_Parent FOREIGN KEY (parent) REFERENCES dailyreports(id) ON UPDATE CASCADE ON DELETE RESTRICT;

但是

id varchar(12) NOT NULL，

dailyreports中的

既不是主要的也不是唯一的。您只能在基表中引用primary或unique的列来创建外键。因此，将列设为关键列或唯一，然后重试。

Answer 2

使C:\OpenGTS_2.6.4\bin>initdb.bat "C:\Program Files\Java\jdk1.8.0_45\bin\java" "-Dfile.encoding=UTF-8" -classpath "C:\OpenGTS_2.6.4\build\lib"\gtsdb.jar;"C:\OpenGTS_2.6.4\build\lib"\gtsutils.jar;"C:\OpenGTS_2.6.4\build\lib"\optdb.jar;"C:\OpenGTS_2.6.4\build\lib"\ruledb.jar;"C:\OpenGTS_2.6.4\build\lib"\bcrossdb.jar;"C:\OpenGTS_2.6.4\build\lib"\custom.jar;"C:\OpenGTS_2.6.4\build\lib"\dmtpserv.jar;"C:\OpenGTS_2.6.4\build\lib"\gtsdmtp.jar; org.opengts.db.DBConfig -conf:"C:\OpenGTS_2.6.4\default.conf" -log.file.enable:false -initTables Version: 2.6.4 [ERROR|DBAdmin.execCommands:1006] SQLException message: Access denied for user 'root'@'localhost' (using password: NO) [ERROR|DBAdmin.execCommands:1007] ==> SQLException: DB create error [jdbc:mysql://localhost:3306/] [ERROR|DBAdmin.execCommands:1007] Message: Access denied for user 'root'@'localhost' (using password: NO) [ERROR|DBAdmin.execCommands:1007] SQLState: 28000 [ERROR|DBAdmin.execCommands:1007] ErrorCode: 1045 [DBAdmin.execCommands:1007] java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: NO) java.sql.SQLException: Access denied for user 'root'@'localhost' (using password: NO) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:998) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3835) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3771) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:870) at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1659) at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1206) at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2239) at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2270) at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2069) at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:794) at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:44) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:422) at com.mysql.jdbc.Util.handleNewInstance(Util.java:389) at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:399) at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:325) at java.sql.DriverManager.getConnection(DriverManager.java:664) at java.sql.DriverManager.getConnection(DriverManager.java:247) at org.opengts.dbtools.DBConnection.getConnection(DBConnection.java:809) at org.opengts.dbtools.DBConnection.createStatement(DBConnection.java:945) at org.opengts.dbtools.DBConnection.createStatement(DBConnection.java:933) at org.opengts.dbtools.DBConnection._executeUpdate(DBConnection.java:1188) at org.opengts.dbtools.DBConnection.executeUpdate(DBConnection.java:1143) at org.opengts.dbtools.DBConnection.executeUpdate(DBConnection.java:1124) at org.opengts.dbtools.DBProvider.createDatabase(DBProvider.java:1699) at org.opengts.dbtools.DBAdmin.execCommands(DBAdmin.java:995) at org.opengts.db.DBConfig._main(DBConfig.java:2036) at org.opengts.db.DBConfig.main(DBConfig.java:2180)与Not Null一起成为唯一。

或将其设为主键

无法在MySQL中创建外键约束

2 个答案: