Replace specific text in csv via commandline

Question

I have data in csv format that gets output from SQL Server. The data has some NULL and N.A. values written out which makes a column ch

Answer 1

@echo off
    setlocal enableextensions enabledelayedexpansion

    (for /f "tokens=*" %%f in (a.csv) do if not "%%f"=="" (
            set "line=%%f"
            set "line=!line:NULL=-1!"
            set "line=!line:N.A.=-2!"
            echo(!line!
    )) > b.csv

    endlocal

This will work if, as stated by OP, the file is in the format indicated, containing only integers, NULL and N.A., or at least it does not include special characters.