问题描述
packagecom.jdbc;importjava.sql.Connection;importjava.sql.DriverManager;importjava.sql.ResultSet;importjava.sql.SQLException;importjava.sql.Statement;publicclassDemo1{/***@paramargs*@throwsClassNotFoundException*@throwsSQLException*/publicstaticvoidmain(String[]args)throwsClassNotFoundException,SQLException{Stringurl="jdbc:mysql://localhost:3306/day14";Stringuser="root";Stringpassword="111";//1.加载MySql驱动Class.forName("com.mysql.jdbc.Driver");//2.获得与数据库的连接Connectioncon=DriverManager.getConnection(url,user,password);//3.获得用于向数据库发送sql的statement对象Statementst=con.createStatement();//4.向数据库发送sql语句Stringsql="select*fromuesr";ResultSetrs=st.executeQuery(sql);//5.从结果集中取数据while(rs.next()){System.out.println(rs.getObject("id"));System.out.println(rs.getObject("name"));System.out.println(rs.getObject("password"));System.out.println(rs.getObject("email"));System.out.println(rs.getObject("birthday"));}//释放资源rs.close();st.close();con.close();}}开发Android的Eclipse运行结果如下:java.lang.NoClassDefFoundError:com/jdbc/Demo1Causedby:java.lang.ClassNotFoundException:com.jdbc.Demo1atjava.net.URLClassLoader$1.run(UnknownSource)atjava.security.AccessController.doPrivileged(NativeMethod)atjava.net.URLClassLoader.findClass(UnknownSource)atjava.lang.ClassLoader.loadClass(UnknownSource)atsun.misc.Launcher$AppClassLoader.loadClass(UnknownSource)atjava.lang.ClassLoader.loadClass(UnknownSource)atjava.lang.ClassLoader.loadClassInternal(UnknownSource)Exceptioninthread"main"原始Eclipse版本运行结果如下:Exceptioninthread"main"com.mysql.jdbc.exceptions.MySQLSyntaxErrorException:Table'day14.uesr'doesn'texistatcom.mysql.jdbc.SQLError.createSQLException(SQLError.java:936)atcom.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2985)atcom.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1631)atcom.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1723)atcom.mysql.jdbc.Connection.execSQL(Connection.java:3277)atcom.mysql.jdbc.Connection.execSQL(Connection.java:3206)atcom.mysql.jdbc.Statement.executeQuery(Statement.java:1232)atcom.jdbc.Demo1.main(Demo1.java:33)MyEclipse运行结果如下:Exceptioninthread"main"java.lang.Error:Unresolvedcompilationproblem:com.mysqlcannotberesolvedtoatypeatcom.jdbc.Demo1.main(Demo1.java:24)我感觉每次第一个和第三个都只是用之前的class文件
解决方案
解决方案二:
'day14.uesr'你这张表不存在把
解决方案三:
你的user表是放在哪个用户下的,可能是它找不到你的那个user表。