Describe: c# EXCEL writing multi-threaded operation, including uploading and importing a database

File list(Click to check if it's the file you need, and recomment it at the bottom):
  ExcelTest
  .........\bin
  .........\...\Debug
  .........\...\.....\ExcelTest.exe
  .........\...\.....\ExcelTest.pdb
  .........\...\.....\ExcelTest.vshost.exe
  .........\ExcelHelper.cs
  .........\ExcelTest.csproj
  .........\obj
  .........\...\Debug
  .........\...\.....\ExcelTest.exe
  .........\...\.....\ExcelTest.pdb
  .........\...\.....\TempPE
  .........\...\ExcelTest.csproj.FileList.txt
  .........\Program.cs
  .........\Properties
  .........\..........\AssemblyInfo.cs
  TestExcelHelper
  ...............\AuthoringTests.txt
  ...............\bin
  ...............\...\Debug
  ...............\...\.....\ExcelTest.exe
  ...............\...\.....\ExcelTest.pdb
  ...............\...\.....\TestExcelHelper.dll
  ...............\...\.....\TestExcelHelper.pdb
  ...............\ExcelHelperTest.cs
  ...............\obj
  ...............\...\Debug
  ...............\...\.....\ResolveAssemblyReference.cache
  ...............\...\.....\TempPE
  ...............\...\.....\TestExcelHelper.dll
  ...............\...\.....\TestExcelHelper.pdb
  ...............\...\TestExcelHelper.csproj.FileList.txt
  ...............\Properties
  ...............\..........\AssemblyInfo.cs
  ...............\TestExcelHelper.csproj
  ...............\VSCodeGenAccessors.cs
  TestResults
  ExcelTest.sln
  ExcelTest.suo
  ExcelTest.vsmdi
  localtestrun.testrunconfig
  ExcelHelper.wps