jdbc中的未知数据库

Question

我正在使用JDBC和新的.但我一直得到这个运行时异常:

   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)");
        } 

如何让这段代码工作？我只是JDBC的初学者....

对于上述代码; PASS ="passowrd",USER ="root"

我遇到了通过这个网站修复的端口问题

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。

希望这可以帮助。

Answer 2

请检查mysql数据库是否存在数据库名称' kholofedb '

我想你还没有创造

如果没有创建它及其相关表，请检查一次

Answer 3

我有同样的问题，发现它的原因是： 这里的数据库名称是CASE SENSITIVE！ 所以，我试图使用像“test2”这样的数据库名称进行连接，但数据库名称实际上是“Test2”。