Saturday, February 23, 2019

Apache POI - Database

This chapter explains how the POI library interacts with a database. With the help of JDBC, you can retrieve data from a database and insert that data into a spreadsheet using the POI library. Let us consider MySQL database for SQL operations.

Write into Excel from Database

Let us assume the following employee data table called emp_tbl is to be retrieved from the MySQL database test.
EMP IDEMP NAMEDEGSALARYDEPT
1201GopalTechnical Manager45000IT
1202ManishaProof reader45000Testing
1203MasthanvaliTechnical Writer45000IT
1204KiranHr Admin40000HR
1205KranthiOp Admin30000Admin
Use the following code to retrieve data from a database and insert the same into a spreadsheet.
import java.io.File;
import java.io.FileOutputStream;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

import org.apache.poi.xssf.usermodel.XSSFCell;
import org.apache.poi.xssf.usermodel.XSSFRow;
import org.apache.poi.xssf.usermodel.XSSFSheet;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

public class ExcelDatabase {
   public static void main(String[] args) throws Exception {
      Class.forName("com.mysql.jdbc.Driver");
      Connection connect = DriverManager.getConnection( 
         "jdbc:mysql://localhost:3306/test" , 
         "root" , 
         "root"
      );
      
      Statement statement = connect.createStatement();
      ResultSet resultSet = statement.executeQuery("select * from emp_tbl");
      XSSFWorkbook workbook = new XSSFWorkbook(); 
      XSSFSheet spreadsheet = workbook.createSheet("employe db");
      
      XSSFRow row = spreadsheet.createRow(1);
      XSSFCell cell;
      cell = row.createCell(1);
      cell.setCellValue("EMP ID");
      cell = row.createCell(2);
      cell.setCellValue("EMP NAME");
      cell = row.createCell(3);
      cell.setCellValue("DEG");
      cell = row.createCell(4);
      cell.setCellValue("SALARY");
      cell = row.createCell(5);
      cell.setCellValue("DEPT");
      int i = 2;

      while(resultSet.next()) {
         row = spreadsheet.createRow(i);
         cell = row.createCell(1);
         cell.setCellValue(resultSet.getInt("eid"));
         cell = row.createCell(2);
         cell.setCellValue(resultSet.getString("ename"));
         cell = row.createCell(3);
         cell.setCellValue(resultSet.getString("deg"));
         cell = row.createCell(4);
         cell.setCellValue(resultSet.getString("salary"));
         cell = row.createCell(5);
         cell.setCellValue(resultSet.getString("dept"));
         i++;
      }

      FileOutputStream out = new FileOutputStream(new File("exceldatabase.xlsx"));
      workbook.write(out);
      out.close();
      System.out.println("exceldatabase.xlsx written successfully");
   }
}
Let us save the above code as ExcelDatabase.java. Compile and execute it from the command prompt as follows.
$javac ExcelDatabase.java
$java ExcelDatabase
It will generate an Excel file named exceldatabase.xlsx in your current directory and display the following output on the command prompt.
exceldatabase.xlsx written successfully
The exceldatabase.xlsx file looks as follows.
Excel Database

No comments:

Post a Comment

Popular Posts