CREATE TABLE table_23397386_2 (viewers__millions_ VARCHAR2, airdate VARCHAR2)

How many million viewers watched the episode that aired on March 28, 2010?
SELECT viewers__millions_ FROM table_23397386_2 WHERE airdate = "March 28, 2010"
SELECT "viewers__millions_" FROM "table_23397386_2" WHERE "March 28, 2010" = "airdate"