java - jdbc 中的未知数据库

Question

我正在使用 JDBC 并且是新手。但我不断收到此运行时异常:

   connecting to psysical database...
   com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown database 'kholofelodb'
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1052)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3609)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3541)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:943)
at com.mysql.jdbc.MysqlIO.secureAuth411(MysqlIO.java:4113)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1308)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2336)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2369)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
at java.sql.DriverManager.getConnection(DriverManager.java:579)
at java.sql.DriverManager.getConnection(DriverManager.java:221)
at com.psybergate.database.SimbleCode.main(SimbleCode.java:22)

这是给出的代码

try {
            String connectionURL =      "jdbc:mysql://localhost:3306/kholofelodb";
            Class.forName("com.mysql.jdbc.Driver");

            System.out.println("connecting to psysical database...");
            Connection conn = DriverManager.getConnection(connectionURL, USER,
                    PASS);

            Statement statement = conn.createStatement();
            System.out.println("Connection has been made");

            Scanner keyBoardScanner = new Scanner(System.in);
            System.out.println("Enter table name:");
            String tableName = keyBoardScanner.nextLine();

            System.out.println("Creating table...");
            statement.executeQuery("create table " + tableName
                    + " (name , age ,salary)");
            System.out.println("Table successfully created");
            System.out.println("Inserting data into the table ...");
            statement.executeUpdate("insert into " + tableName
                    + "values (kholofelo , 21 , 9969696)");
        } 

如何让这段代码起作用？我只是 JDBC 的初学者....

对于上面的代码； PASS = "passowrd", USER = "root"

我的端口有问题，已通过此站点修复

非常感谢

Answer 1

登录mysql服务器，

$ mysql -u <username> -p<password>

列出所有数据库，

mysql> show databases;

检查您的数据库名称是否存在，

+--------------------+
| Database           |
+--------------------+
| information_schema |
| kholofelodb        |
| mysql              |
| phpmyadmin         |
+--------------------+

请注意:数据库名称区分大小写。

希望这对您有所帮助。