which column of sql table is equal to a variable

[zivoni]

But you are trying to get rows with id = "f1", not rows with id = "789" - you have no variable substitution/expansion in your select string. So you are getting the correct response (unless you have row with id "f1" in your table ... ). 

Either format/construct your select string with your variable - you can do something like:

select_string = 'select * from bla where id = "{}";'.format(f1)

or use (and thats better solution, if its available) a variable substitution provided by a database connection - its usually something like:

cur.execute("select * from bla where id = ?", (f1,))

exact syntax might vary according to the database used.