Reading Data from Linux C

What is best way to get one row from a mysql table (with many columns) so I can use several several fields from that row for calculations in a C program?
After executing a succesful SELECT command using mysql_query, is there an alternative to using mysql_store_result?

Reading Data from MYSQL using Linux C

What is best way to get one row from a mysql table (with many columns) so I can use several several fields from that row for calculations in a C program?
After executing a succesful SELECT command using mysql_query, is there an alternative to using mysql_store_result?

Add to Path in Windows 10

What is the best/easiest way to add a directory to 'Path' when starting a CMD (MS-DOS) window? It used to be possible to do this with an AUTOEXEC.BAT file in XP.