PreparedStatement类从Statement中继承来。

可以将SQL语句传给数据库做编译处理，即在执行的SQL语句中包含一个或多个IN参数，可以设置IN参数值多次执行SQL语句，不必重新给出SQL语句，提高了执行SQL语句的效率

import com.mysql.jdbc.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.util.Properties; /**  * Created by I am master on 2016/10/3.  */ public class preparedstatement {
      public static void main(String[] args)throws Exception {
         Class.forName("com.mysql.jdbc.Driver");        String url="jdbc:mysql://localhost:3306/job";        Properties info=new Properties();        info.put("user","root");        info.put("password","root");        Connection connection= (Connection)DriverManager.getConnection(url,info);         //IN参数用？表示 String sql="select * from jobs where min_lvl>=? and max_lvl<=?";         PreparedStatement preparedStatement=connection.prepareStatement(sql);         //在执行查询操作之前必须对每个IN参数进行设置         //设置IN参数的语法格式：preparedStatement.setXXX(position,value) position为IN参数在SQL语句中的位置，valu为参数被设置的值         preparedStatement.setInt(1,160);         preparedStatement.setInt(2,300);         ResultSet rs=preparedStatement.executeQuery();         while (rs.next()){
              String job_id=rs.getString("job_id");             String job_desc=rs.getString("job_desc");             String min_lvl=rs.getString("min_lvl");             String max_lvl=rs.getString("max_lvl");             System.out.print(job_id);             System.out.print(job_desc);             System.out.print(min_lvl);             System.out.println(max_lvl);         }     } }