ps.executeUpdate（sql）抛出com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：你的SQL语法有错误

-2

我正在学习使用mysql在Xampp服务器上的简单数据库连接。数据库在phpmyadmin上实现。我在NetBeans IDE中从java servlet访问数据库。ps.executeUpdate（sql）抛出com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：你的SQL语法有错误

package com.DBcheck; 

import java.io.IOException; 
import java.io.PrintWriter; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.PreparedStatement; 
import java.sql.SQLException; 
import java.util.logging.Level; 
import java.util.logging.Logger; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import java.sql.*; 


public class NewServlet extends HttpServlet { 


protected void processRequest(HttpServletRequest request, HttpServletResponse response) 
     throws ServletException, IOException, ClassNotFoundException, SQLException { 
    response.setContentType("text/html;charset=UTF-8"); 
    try (PrintWriter out = response.getWriter()) { 
     /* TODO output your page here. You may use following sample code. */ 
     Class.forName("com.mysql.jdbc.Driver"); 

     Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/profilebuilder","root",""); 

     String sql="insert into signupdetailstable(FirstName) values(?)"; 
     PreparedStatement ps=con.prepareStatement(sql); 

     ps.setString(1, "nirmal");   
     int log=ps.executeUpdate(sql); 
     out.println(log); 
    } 
} 


@Override 
protected void doGet(HttpServletRequest request, HttpServletResponse response) 
     throws ServletException, IOException { 
    try { 
     processRequest(request, response); 
    } catch (ClassNotFoundException ex) { 
     Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex); 
    } catch (SQLException ex) { 
     Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex); 
    } 
} 


@Override 
protected void doPost(HttpServletRequest request, HttpServletResponse response) 
     throws ServletException, IOException { 
    try { 
     processRequest(request, response); 
    } catch (ClassNotFoundException ex) { 
     Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex); 
    } catch (SQLException ex) { 
     Logger.getLogger(NewServlet.class.getName()).log(Level.SEVERE, null, ex); 
    } 
} 


@Override 
public String getServletInfo() { 
    return "Short description"; 
}// </editor-fold> 

}

此代码给我看像

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '?)' at line 1 
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) 
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) 
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) 
at java.lang.reflect.Constructor.newInstance(Constructor.java:422) 
at com.mysql.jdbc.Util.handleNewInstance(Util.java:377) 
at com.mysql.jdbc.Util.getInstance(Util.java:360) 
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:978) 
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3887) 
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3823) 
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2435) 
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2582) 
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2526) 
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1618) 
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1549) 
at com.DBcheck.NewServlet.processRequest(NewServlet.java:50) 
at com.DBcheck.NewServlet.doGet(NewServlet.java:68) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:687) 
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) 
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682) 
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318) 
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160) 
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734) 
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673) 
at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99) 
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174) 
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:415) 
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:282) 
at com.sun.enterprise.v3.services.impl.ContainerMapper$HttpHandlerCallable.call(ContainerMapper.java:459) 
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:167) 
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:201) 
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:175) 
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:235) 
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:284) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:201) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:133) 
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:112) 
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77) 
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:561) 
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:112) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:117) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:56) 
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:137) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:565) 
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:545) 
at java.lang.Thread.run(Thread.java:745)

错误谁能帮助一下这个例外想说的？

来源

2016-10-02 Nirmal Purohit

只要使用'main（）'方法使用简单的Java应用程序类可以重现相同的问题，请不要使用[servlets]标记。这表明它与特定的servlet无关。 – BalusC

这是一个很容易犯的错误。您使用Statement#executeUpdate(String)代替PreparedStatement#executeUpdate()：

相反，你想：

int log=ps.executeUpdate(); 
// Nothing here ---------^

的唯一原因PreparedStatement具有executeUpdate(String)是，它的Statement一个子类。但随着PreparedStatement，您构建语句，你做得正确时提供SQL：

PreparedStatement ps=con.prepareStatement(sql);

然后你供应也做不executeUpdate。

来源

2016-10-02 14:39:45

是的，你可能会认为这是API设计中的一个缺陷。（当然可以） –

感谢您的快速帮助。你的建议奏效了。 @TJCrowder –

ps.executeUpdate（sql）抛出com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException：你的SQL语法有错误

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