将sql查询结果导出到csv或excel

Question

我想将sql查询的结果写入csv或excel文件并将其保存在特定的文件夹中.我想知道是否可以使用java程序实现这一点,该程序可以重用于任何sql查询结果.我会还想知道这是否可以用于不同类型的数据库(oracle,mysql,MS sql server等).我打算将保存的文件附加到电子邮件中(这可能直接将sql查询结果导出到电子邮件中).请帮忙.

Answer 1

使用openCSV API,您可以在csv文件中导出数据.

CSVWriter writer = new CSVWriter(new FileWriter("yourfile.csv"), '\t');
Boolean includeHeaders = true;

java.sql.ResultSet myResultSet = .... //your resultset logic here

writer.writeAll(myResultSet, includeHeaders);

writer.close();

Answer 2

最简单的解决方案。

主要方法

 private List<String> resultSetArray=new ArrayList<>();
 private String username ="";     // Enter DB Username
 private String password = "";    // Enter DB password
 private String url = "";         // Enter DB URL

 Connection connection=DriverManager.getConnection(url,user,pwd);   

 public static void main(String args[]) throws Exception{

        fetchDataFromDatabase("SQL queries", connection);
        printToCsv(resultArray);                

 }

从数据库中获取数据

下面的代码计算表中的列数，并存储在结果数组中。

private void fetchDataFromDatabase(String selectQuery,Connection connection) throws  Exception{
            try {


                Statement stmt = connection.createStatement();
                ResultSet rs = stmt.executeQuery(selectQuery);
                int numCols = rs.getMetaData().getColumnCount();

                while(rs.next()) {
                    StringBuilder sb = new StringBuilder();

                    for (int i = 1; i <= numCols; i++) {
                        sb.append(String.format(String.valueOf(rs.getString(i))) + " ");

                    }
                    resultSetArray.add(sb.toString());

                }

            } catch (SQLException e) {
                LOGGER.error("Sql exception " + e.getMessage());
            }

        }

打印到CSV

 public static void printToCsv(List<String> resultArray) throws Exception{

        File csvOutputFile = new File(file_name);
        FileWriter fileWriter = new FileWriter(csvOutputFile, false);


        for(String mapping : resultArray) {
            fileWriter.write(mapping + "\n");
         }

        fileWriter.close();

    }

Answer 3

这是一个例子：

import java.io.*;
import java.sql.*;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFCell;

public class ExcelFile {
        public static void main(String[] args) {
                try {
                        Class.forName("com.mysql.jdbc.Driver").newInstance();
                        Connection connection = DriverManager.getConnection(
                                        "jdbc:mysql://localhost:3306/test", "root", "root");
                        PreparedStatement psmnt = null;
                        Statement st = connection.createStatement();
                        ResultSet rs = st.executeQuery("Select * from student");

                        HSSFWorkbook wb = new HSSFWorkbook();
                        HSSFSheet sheet = wb.createSheet("Excel Sheet");
                        HSSFRow rowhead = sheet.createRow((short) 0);
                        rowhead.createCell((short) 0).setCellValue("Roll No");
                        rowhead.createCell((short) 1).setCellValue("Name");
                        rowhead.createCell((short) 2).setCellValue("Class");
                        rowhead.createCell((short) 3).setCellValue("Marks");
                        rowhead.createCell((short) 4).setCellValue("Grade");

                        int index = 1;
                        while (rs.next()) {

                                HSSFRow row = sheet.createRow((short) index);
                                row.createCell((short) 0).setCellValue(rs.getInt(1));
                                row.createCell((short) 1).setCellValue(rs.getString(2));
                                row.createCell((short) 2).setCellValue(rs.getString(3));
                                row.createCell((short) 3).setCellValue(rs.getInt(4));
                                row.createCell((short) 4).setCellValue(rs.getString(5));
                                index++;
                        }
                        FileOutputStream fileOut = new FileOutputStream("c:\\excelFile.xls");
                        wb.write(fileOut);
                        fileOut.close();
                        System.out.println("Data is saved in excel file.");
                        rs.close();
                        connection.close();
                } catch (Exception e) {
                }
        }
}

参考