parameters = ['a', 'b', 'c']
query = "SELECT * FROM foo WHERE bar IN (%s)" % (', '.join(parameters))

SELECT * FROM foo WHERE bar IN (a, b, c, d)

SELECT * FROM foo WHERE bar IN ('a', 'b', 'c', 'd')

(', '.join('"' + item + '"' for item in parameters))

query = "SELECT * FROM foo WHERE bar IN %s" % repr(tuple(map(str,parameters)))

parameters = ['a', 'b', 'c']
', '.join(map(lambda x: "'" + x + "'", parameters))

"SELECT * FROM foo WHERE bar IN ('{0}')".format("', '".join(parameters))

"SELECT * FROM foo WHERE bar IN ('%s')" % "', '".join(parameters)