Which date's visitor was jazz, when the leading scorer was Mehmet Okur (22)?
CREATE TABLE "april" (
  "date" text,
  "visitor" text,
  "score" text,
  "home" text,
  "leading_scorer" text,
  "record" text
);
SELECT "date" FROM "april" WHERE "visitor"='jazz' AND "leading_scorer"='mehmet okur (22)';