CREATE TABLE table_201_46 (id DECIMAL, "name" TEXT, "position" TEXT, "length\ [km]" DECIMAL, "drainage basin area\ [km2]" DECIMAL, "confluence\ [by lahn-km]" DECIMAL, "mouth elevation\ [m above msl]" DECIMAL)

which tributary has their position to the left with a length of 46.6 km ?
SELECT "name" FROM table_201_46 WHERE "position" = 'left' AND "length\n[km]" = 46.6
SELECT "name" FROM "table_201_46" WHERE "length\n[km]" = 46.6 AND "position" = 'left'