CREATE TABLE table_15891 ("Player" TEXT, "Years Played" TEXT, "Total W-L" TEXT, "Singles W-L" TEXT, "Doubles W-L" TEXT)

what's the singles w-l for kim doo-hwan
SELECT "Singles W-L" FROM table_15891 WHERE "Player" = 'Kim Doo-Hwan'
SELECT "Singles W-L" FROM "table_15891" WHERE "Player" = 'Kim Doo-Hwan'