CREATE TABLE table_31879 ("Played in" CLOB, "Matches" CLOB, "Lost" CLOB, "Drawn" CLOB, "Points for" CLOB, "Points against" CLOB)

The 51 points against, how many are for?
SELECT "Points for" FROM table_31879 WHERE "Points against" = '51'
SELECT "Points for" FROM "table_31879" WHERE "Points against" = '51'