java - 如何为 mysql 5.5.44 创建触发器？

Question

s = "CREATE TABLE " + tableName +"\n" +
    "(\n" +
    "    " + tablelower + "_currentid INT PRIMARY KEY AUTO_INCREMENT,\n" +
    "    " + tablelower + "_id VARCHAR(8) NOT NULL,\n" +
    "    " + tablelower + "_name VARCHAR(45) NOT NULL,\n" +
    "    " + tablelower + "_type VARCHAR(45) NOT NULL,\n" +
    "    " + tablelower + "_topic  VARCHAR(255) NOT NULL,\n" +
    "    " + tablelower + "_pin VARCHAR(6) NOT NULL,\n" +
    "    " + tablelower + "_device VARCHAR(100) NOT NULL,\n" +
    "    " + tablelower + "_device_id INT NOT NULL,\n" +
    "    FOREIGN KEY(" + tablelower + "_device_id) REFERENCES Devices(device_currentid)\n" +
    ");\n" +
    "\n" +
    " delimiter | \n" +
    " CREATE TRIGGER " + tablelower + "_trigger BEFORE INSERT ON " + tableName + 
    " FOR EACH ROW\n" +
    " BEGIN\n" +
    "   SET new." + tablelower + "_id = CONCAT('" + topic + "',LPAD((SELECT AUTO_INCREMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = '" + tableName + "'),4,'0'));\n" +
    "   SET new." + tablelower + "_topic = CONCAT((SELECT device_topic FROM Devices WHERE device_name LIKE new." + tablelower + "_device),'/',(new." + tablelower + "_id));\n" +
    " END;\n" +
    " | \n" +
    " delimiter ;";

    mysqlconn.createStatement().execute(s);

上面的代码将创建一个表和一个触发器，其中给定名称为 tableName 和 tablelower，它们是字符串变量。这是我写的第一个版本，我收到以下错误:

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 'delimiter | 
CREATE TRIGGER tablename_trigger BEFORE INSERT ON tablename FO' at line 14

在谷歌帮助下我找到了这个线程Error while creating trigger through JDBC on mysql5.5和文档 http://dev.mysql.com/doc/refman/5.5/en/trigger-syntax.html我已经将我的代码更改为 StringBuilder:

            tableCreation.append("CREATE TABLE " + tableName);
            tableCreation.append("(");
            tableCreation.append(tablelower + "_currentid INT PRIMARY KEY AUTO_INCREMENT,");
            tableCreation.append(tablelower + "_id VARCHAR(10) NOT NULL,");
            tableCreation.append(tablelower + "_name VARCHAR(45) NOT NULL,");
            tableCreation.append(tablelower + "_type VARCHAR(45) NOT NULL,");
            tableCreation.append(tablelower + "_topic  VARCHAR(255) NOT NULL,");
            tableCreation.append(tablelower + "_pin VARCHAR(6) NOT NULL,");
            tableCreation.append(tablelower + "_device VARCHAR(100) NOT NULL,");
            tableCreation.append(tablelower + "_device_id INT NOT NULL,");
            tableCreation.append("FOREIGN KEY(" + tablelower + "_device_id) REFERENCES Devices(device_currentid)");
            tableCreation.append(" ); ");

            tableCreation.append("DELIMITER // ");
            tableCreation.append(" CREATE");
            tableCreation.append(" TRIGGER " + tablelower + "id_trigger ");
            tableCreation.append(" BEFORE INSERT");
            tableCreation.append(" ON " + tableName + " FOR EACH ROW");
            tableCreation.append(" BEGIN");
            tableCreation.append(" SET new." + tablelower + "_id = CONCAT('" + topic + "',LPAD((SELECT AUTO_INCREMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = '" + tableName + "'),4,'0'));");
            tableCreation.append(" SET new." + tablelower + "_topic = CONCAT((SELECT device_topic FROM Devices WHERE device_name LIKE new." + tablelower + "_device),'/',(new." + tablelower + "_id));");
            tableCreation.append(" END;//");
            tableCreation.append("DELIMITER ; ");

            mysqlconn.createStatement().execute(tableCreation.toString());

但在这些更改之后我仍然收到此错误:

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 'DELIMITER // CREATE TRIGGER reedswitchid_trigger BEFORE INSERT ON ReedSwitches' at line 1.

我正在通过 java 执行此操作，MySQL 服务器位于 Raspberry pi 2 上。 如需更多信息，请评论并注意我是 SQL 初学者。谢谢

编辑:

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 'SET >new.lightsensor_topic = CONCAT((SELECT device_topic FROM Devices WHERE >devic' at line 1. Exiting

             tabl = "CREATE TABLE " + tableName  +
                "(" + " " + tablelower + "_currentid INT PRIMARY KEY AUTO_INCREMENT, " +
                tablelower + "_id VARCHAR(8) NOT NULL, " +
                tablelower + "_name VARCHAR(45) NOT NULL, " +
                tablelower + "_type VARCHAR(45) NOT NULL, " +
                tablelower + "_topic  VARCHAR(255) NOT NULL, " +
                tablelower + "_pin  VARCHAR(6) NOT NULL, " +
                tablelower + "_device VARCHAR(100) NOT NULL, " +
                tablelower + "_device_id INT NOT NULL, " +
                "FOREIGN KEY(" + tablelower + "_device_id) REFERENCES Devices(device_currentid)" +
                ")";
             trigg=
                " CREATE TRIGGER " + tablelower + "_trigger BEFORE INSERT ON " + tableName + 
                " FOR EACH ROW" +
                "   SET new." + tablelower + "_id = CONCAT('" + topic + "',LPAD((SELECT AUTO_INCREMENT FROM information_schema.TABLES WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = '" + tableName + "'),4,'0'))" +
                "   SET new." + tablelower + "_topic = CONCAT((SELECT device_topic FROM Devices WHERE device_name LIKE new." + tablelower + "_device),'/',(new." + tablelower + "_id))" +
                " END";

        mysqlconn = data.getConnection();
        mysqlconn.createStatement().execute(tabl);
        mysqlconn.createStatement().execute(trigg);

Answer 1

JDBC Stateent#executeXXX 方法旨在执行单个 SQL 语句，而不是同时执行多个语句。
即使某些数据库/驱动程序实现允许这样做，这也是一种非标准方式，并且不可移植，因此请不要使用它。

将您的代码分成两个语句:

String s1 = "CREATE TABLE ( ....... )";
String s2 = "CREATE TRIGGER .......END";
 mysqlconn.createStatement().execute( s1 );
 mysqlconn.createStatement().execute( s2 );

两个重要说明:

• 不要在 JDBC 中的 SQL 命令末尾使用分号 ;
• 不要使用DELIMITER x 命令——它不是SQL 命令，而是mysql-client 命令，数据库无法识别它