CREATE TABLE table_name_8 (share NUMBER, air_date VARCHAR2, viewers VARCHAR2)

What is the lowest share with an air date of March 21, 2008 and had viewers larger than 5.15?
SELECT MIN(share) FROM table_name_8 WHERE air_date = "march 21, 2008" AND viewers > 5.15
SELECT MIN("share") FROM "table_name_8" WHERE "air_date" = "march 21, 2008" AND "viewers" > 5.15