OpenCsv | SQL |只写标题，而不写表内容 [英] OpenCsv | SQL | Writes only the header and not the table content

问题描述

我试图通过Java执行一条SQL语句，并将结果写入.csv文件.

I am trying to execute an SQL statement through Java and write the results to a .csv file.

我正在使用 OJDBC.jar (v7)连接到Oracle 11g DB和 OPENCSV.jar (v3.8)来创建和写入Excel.

I am using OJDBC.jar (v7) to connect to Oracle 11g DB and OPENCSV.jar (v3.8) for creating and writing into the excel.

表格结果打印效果很好.我正在使用管道将记录中的所有列值分开.

Table result is printing very well. I am using pipe to separate all the column values in a record.

但是，在生成的csv文件中，我只能看到表的列名，而根本看不到任何数据！可能是什么原因?请帮忙.

However, on the generated csv file, i see only the column names of the table and no data at all! What might be the reason? Please help.

package test;

import java.io.FileWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

import com.opencsv.CSVWriter;



public class AllInOne
{

static String hostIP="255.255.255.255";
static String PortNum="1521";
static String ServiceName="SNAME";
static String un="USER";
static String pw="PWD";
static int columnCount;
static String row="";


  public static void main(String[] args) throws Exception
  {
    String addr = "jdbc:oracle:thin:@"+hostIP+":"+PortNum+":"+ServiceName;
    Class.forName("oracle.jdbc.OracleDriver");
    Connection con = DriverManager.getConnection(addr,un,pw);
    Statement stat = con.createStatement();
    ResultSet rs = stat.executeQuery("select * from t_employee_info where rownum <6");

    ResultSetMetaData resultSetMetaData = rs.getMetaData();
    columnCount = resultSetMetaData.getColumnCount();

    while (rs.next())
    {

        for (int i = 1; i <= columnCount; i++) 
        {
            row += rs.getString(i) + "|";
        }

        System.out.println(row);
        row = "";
    }

    FileWriter fw=new FileWriter("C:/Users/myName/Desktop/Folder/CSVfile.csv");
    CSVWriter writer = new CSVWriter(fw);
    writer.writeAll(rs,true);
    writer.close();  
    fw.close();
    stat.close();
    con.close();
    System.out.println("File Generated");

  }

}

推荐答案

Shreyas，您已经对结果集进行了一次迭代.因此，您的选择是在RS上迭代到变量(例如|分隔值的列表)时将值存储起来，并将它们传递给CSV Writer上的方法.

Shreyas , you have already iterated over the result set once. So the choices you have are to store the values as you iterate over the RS to a variable (say a list of | delimited values) and pass them to a method on CSV Writer.

第二个选择是实际使用rs.first()(前提是您具有可滚动的结果集)，然后将其传递给该方法.但是，这不是一个好习惯

A second option will be to actually use rs.first() (provided you have a scrollable result set) and then pass it to the method. This is however not a great practice

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