CREATE TABLE table_7698 ("Material" CLOB, "Formula" CLOB, "Refractive index ( es )  589.3nm" CLOB, "Hardness  (  Mohs' scale  ) " CLOB, "Density  ( g/cm 3  ) " CLOB, "State of the art" CLOB)

Which formula has a refractive index 589.3 at 1.97?
SELECT "Formula" FROM table_7698 WHERE "Refractive index(es) 589.3nm" = '1.97'
SELECT "Formula" FROM "table_7698" WHERE "Refractive index(es) 589.3nm" = '1.97'