使用C＃将Postgres DB导出到excel

Question

I need to export Postgres DB (having around 20 tables) to excel using C#. I need to implement some logic on the data from DB and then need to export it. Any idea of how to export all data using c#?

Answer 1

using Npgsql;
using OfficeOpenXml;  // Nuget EPPlus
using System.IO;

EPPlus has a one-step method to export a data table into a spreadsheet, so if you leveraged this, you should be able to loop through your queries and export each one to a unique sheet.

Something like this (untested but should be 99% there) should do the trick:

FileInfo fi = new FileInfo("foo.xlsx");
ExcelPackage excel = new ExcelPackage(fi);

int sheet = 1;

foreach (string sql in sqlQueries)
{
    DataTable dt = new DataTable();
    NpgsqlCommand cmd = new NpgsqlCommand(sql, conn);
    NpgsqlDataAdapter da = new NpgsqlDataAdapter(cmd);
    da.Fill(dt);

    ExcelWorksheet ws = excel.Workbook.Worksheets.Add(string.Format("Sheet{0}", sheet++));
    ws.Cells["A1"].LoadFromDataTable(dt, true);
}

excel.Save();

Of course, I'd recommend some refinements to deal with datatypes, formatting and the like, but this is the basic construct.

Also, of course, use the IDisposable using liberally.

Answer 2

The problem can be divided into two sub problems

1. Getting Data into c# from postgres.
2. pushing that data into excel.

Now solving a problem at a time

Here is a good article on working with postgres using c#

once you have you data in c# you can use any one of many libraries available for working with Excel using c#

One of them is NPOI

Here is one with example

Happy Coding.!!!