What is the average for the player with 313 runs?
CREATE TABLE "batting_averages" (
  "player" text,
  "matches" real,
  "innings" real,
  "runs" real,
  "average" text,
  "highest_score" text,
  "100s" real,
  "50s" real
);
SELECT "average" FROM "batting_averages" WHERE "runs"=313;