数据库查询错误答案

【问题标题】：Error in database query数据库查询错误
【发布时间】：2014-07-17 07:34:07
【问题描述】：

我正在尝试通过 Java 程序在 MySql 中创建表。用于创建表的数据库查询中似乎存在错误，我无法弄清楚。这是我的java程序

package Registration;



import java.sql.Connection;

import java.sql.DriverManager;

import java.sql.Statement;

import java.sql.ResultSet;

import java.sql.SQLException;




public class StartBatch 
{


    public void startBatch(String batch)

    {


    Connection connection=null;

        String connectionURL = "jdbc:mysql://localhost:3306/Batches";

        Statement stmt;

        ResultSet rs1;


        try

        {

            Class.forName("com.mysql.jdbc.Driver");



        connection = DriverManager.getConnection(connectionURL, "root", "");

             stmt=connection.createStatement();

         rs1=stmt.executeUpdate("CREATE TABLE IF NOT EXISTS `"+batch+"` (\n" +"  `id` int(11) NOT NULL AUTO_INCREMENT,\n" +"  `student` text NOT NULL,\n" +"  `fees` bigint(20) NOT NULL,\n" +"  PRIMARY KEY (`id`)\n" +") ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;");

   //The error is in above query     
    }

                     catch(ClassNotFoundException e){

                            e.printStackTrace();

            }

            catch(SQLException e){

                            e.printStackTrace();

            }

            catch (Exception e){

                            e.printStackTrace();

            }

            finally {

            // Always close the database connection.

            try {

            if (connection != null) connection.close();

            }

            catch (SQLException ignored){

            }


        }

    }

}

错误：

java.lang.RuntimeException: Uncompilable source code - incompatible types: int cannot be converted to java.sql.ResultSet
    at Registration.StartBatch.startBatch(StartBatch.java:39)
    at org.apache.jsp.CreatedBatch_jsp._jspService(CreatedBatch_jsp.java:83)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.netbeans.modules.web.monitor.server.MonitorFilter.doFilter(MonitorFilter.java:393)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

我正在使用 Netbeans 来运行这个类。

【问题讨论】：

请添加堆栈跟踪。
请发布您遇到的错误
如果不添加堆栈跟踪等额外信息，就无法知道发生了什么
connection = DriverManager.getConnection(connectionURL, "root", ""); MySQL 数据库的密码在哪里？在输入有效密码之前，MySQL 数据库不允许您执行任何操作
statement.executeUpdate 不返回 ResultSet，返回一个 int

标签： java mysql sql jdbc

【解决方案1】：

试试这个：

int updt;
    updt=stmt.executeUpdate("CREATE TABLE IF NOT EXISTS " + batch + " (id int(11) NOT NULL AUTO_INCREMENT, student text NOT NULL, fees bigint(20) NOT NULL, PRIMARY KEY (id)) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1");

http://docs.oracle.com/javase/7/docs/api/java/sql/Statement.html#executeUpdate(java.lang.String)

【讨论】：

【解决方案2】：

首先executeUpdate() 用于insert,delete and update 查询，因此您不应将其用于创建表。

如果你想使用execute() 或Statement or PreparedStatement（主要推荐）创建一个返回类型为void 的表。

另外你的stmt.executeUpdate(query)返回int类型不是ResultSet类型请通过Documentation

【讨论】：