CREATE TABLE table_45887 ("Date" CLOB, "Opponent" CLOB, "Venue" CLOB, "Result" CLOB, "Attendance" FLOAT)

What was the attendance on 31 January 2009 when the opponent was Airdrie United?
SELECT AVG("Attendance") FROM table_45887 WHERE "Opponent" = 'airdrie united' AND "Date" = '31 january 2009'
SELECT AVG("Attendance") FROM "table_45887" WHERE "Date" = '31 january 2009' AND "Opponent" = 'airdrie united'