$ cat db.py                           
def a():
    yield f(
        """
        select %s from (values %%s) as t(%s)
        """
    )

def b():
    return (
        """
        select name
        from foo
        """
        % main_table
    )

def c():
    query = (
        """
        select {keys}
        from (values %s) as t(id)
        """
    )

def d():
    query = f"""select t.id
                from {table} t
                {extra}"""


$ cat db.py| isort - | diff -u db.py -
--- db.py	2020-09-29 17:30:57.737760374 +0200
+++ -	2020-09-29 17:31:42.967321279 +0200
@@ -9,7 +9,6 @@
     return (
         """
         select name
-        from foo
         """
         % main_table
     )
@@ -18,12 +17,11 @@
     query = (
         """
         select {keys}
-        from (values %s) as t(id)
+        from values%s import ast, id
         """
     )
 
 def d():
     query = f"""select t.id
-                from {table} t
                 {extra}"""

$ isort -V                            

                 _                 _
                (_) ___  ___  _ __| |_
                | |/ _/ / _ \/ '__  _/
                | |\__ \/\_\/| |  | |_
                |_|\___/\___/\_/   \_/

      isort your imports, so you don't have to.

                    VERSION 5.5.3