java - 使用 JDBC 在 KDB 数据库中执行查询

Question

我能够执行以下代码来从表中选择所有数据:-

package com.jdbc;
import java.sql.*;
//in kdb+3.x and above
//init table with
//\p 5001
//Employees:([]id:0 1 2;firstName:`Charlie`Arthur`Simon;lastName:`Skelton`Whitney`Garland;age:10 20 30;timestamp:.z.p+til 3)
public class Selection{

  static final String JDBC_DRIVER="jdbc";
  static final String DB_URL="jdbc:q:localhost:5001";
  static final String USER="";
  static final String PASS="";
  public static void main(String[] args){
    Connection conn=null;
    Statement stmt=null;
    try{
      Class.forName(JDBC_DRIVER);
      System.out.println("Connecting to database...");
      conn=DriverManager.getConnection(DB_URL,USER,PASS);
      System.out.println("Creating statement...");
      stmt=conn.createStatement();
      ResultSet rs=stmt.executeQuery("SELECT id, firstName, lastName, age,timestamp FROM Employees");
      while(rs.next()){
        long id=rs.getLong("id");
        long age=rs.getLong("age");
        String first=rs.getString("firstName");
        String last=rs.getString("lastName");
        Timestamp timestamp=rs.getTimestamp("timestamp");
        System.out.print("ID: "+id);
        System.out.print(", Age: "+age);
        System.out.print(", FirstName: "+first);
        System.out.println(", LastName: "+last);
        System.out.println(", Timestamp: "+timestamp);
      }
      rs.close();
      stmt.close();
      conn.close();
    }catch(SQLException se){
      se.printStackTrace();
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      try{
        if(stmt!=null)
          stmt.close();
      }catch(SQLException se2){
      }
      try{
        if(conn!=null)
          conn.close();
      }catch(SQLException se){
        se.printStackTrace();
      }
    }
  }
}

但是每当我尝试运行其他查询时，代码都会给我错误，例如，对于以下代码:-

package com.jdbc;
import java.sql.*;

//in kdb+3.x and above
//init table with
//\p 5001
//Employees:([]id:0 1 2;firstName:`Charlie`Arthur`Simon;lastName:`Skelton`Whitney`Garland;age:10 20 30;timestamp:.z.p+til 3)

public class Insertion {

  static final String JDBC_DRIVER="jdbc";
  static final String DB_URL="jdbc:q:localhost:5001";
  static final String USER="";
  static final String PASS="";

  public static void main(String[] args){
    Connection conn=null;
    Statement stmt=null;
    try{
      Class.forName(JDBC_DRIVER);

      System.out.println("Connecting to database...");
      conn=DriverManager.getConnection(DB_URL,USER,PASS);

      System.out.println("Creating statement...");
      stmt=conn.createStatement();
      stmt.executeUpdate("INSERT INTO Employees VALUES(9, 10, 'X', 'Y', " + new java.sql.Timestamp(0) + ")");

      stmt.close();
      conn.close();
    }catch(SQLException se){
      se.printStackTrace();
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      try{
        if(stmt!=null)
          stmt.close();
      }catch(SQLException se2){
      }
      try{
        if(conn!=null)
          conn.close();
      }catch(SQLException se){
        se.printStackTrace();
      }
    }
  }
}

对于此代码，我收到以下错误:-

Connecting to database... Creating statement... java.sql.SQLException: at jdbc.q(jdbc.java:22) at jdbc$co.ex(jdbc.java:26) at jdbc$st.executeUpdate(jdbc.java:89) at com.jdbc.Insertion.main(Insertion.java:27)

即使在我尝试使用聚合函数进行选择查询时，我也会遇到类似的错误。总而言之，我只能做简单的数据选择，不能做任何其他事情。

有什么线索吗？

是否有关于如何使用 JDBC 对 KDB 数据库进行复杂查询的研究链接？

我也尝试过使用准备好的语句(代码如下)，但仍然没有成功:-

package com.jdbc;
import java.sql.*;

//in kdb+3.x and above
//init table with
//\p 5001
//Employees:([]id:0 1 2;firstName:`Charlie`Arthur`Simon;lastName:`Skelton`Whitney`Garland;age:10 20 30;timestamp:.z.p+til 3)

public class Insertion {

  static final String JDBC_DRIVER="jdbc";
  static final String DB_URL="jdbc:q:localhost:5001";
  static final String USER="";
  static final String PASS="";

  public static void main(String[] args){
    Connection conn=null;
    PreparedStatement stmt=null;
    try{
      Class.forName(JDBC_DRIVER);

      System.out.println("Connecting to database...");
      conn=DriverManager.getConnection(DB_URL,USER,PASS);

      System.out.println("Creating statement...");
      stmt=conn.prepareStatement("INSERT INTO Employees(id,firstName,lastName,age,timestamp) VALUES(?, ?, ?, ?, ?)");
  stmt.setInt(1, 10);
  stmt.setString(2, "X");
  stmt.setString(3, "Y");
  stmt.setInt(4, 5);
  stmt.setTimestamp(5, new Timestamp(0));
      stmt.executeUpdate();

      stmt.close();
      conn.close();
    }catch(SQLException se){
      se.printStackTrace();
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      try{
        if(stmt!=null)
          stmt.close();
      }catch(SQLException se2){
      }
      try{
        if(conn!=null)
          conn.close();
      }catch(SQLException se){
        se.printStackTrace();
      }
    }
  }
}

Answer 1

尝试使用 native API 而不是 JDBC。