Oracle 18c

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CREATE TABLE kids (kid_name, money) AS
SELECT 'Alice', 1.23 FROM DUAL UNION ALL
SELECT 'Beryl', 2.34 FROM DUAL UNION ALL
SELECT 'Carol', 4.56 FROM DUAL;
3 rows affected

CREATE TABLE candy (candy_name, price) AS
SELECT 'A', 0.12 FROM DUAL UNION ALL
SELECT 'B', 0.23 FROM DUAL UNION ALL
SELECT 'C', 0.34 FROM DUAL;
3 rows affected

CREATE PROCEDURE sell_random_candy
IS
BEGIN
  LOOP
    MERGE INTO kids dst
    USING (
      SELECT k.ROWID rid,
             c.price
      FROM   kids k
             INNER JOIN candy c
             ON (c.price <= k.money)
      ORDER BY DBMS_RANDOM.VALUE
      FETCH FIRST ROW ONLY
    ) src
    ON (src.rid = dst.ROWID)
    WHEN MATCHED THEN
      UPDATE
      SET money = dst.money - src.price;
    EXIT WHEN SQL%ROWCOUNT = 0;
  END LOOP;
END;
/
BEGIN
  sell_random_candy;
END;
/
1 rows affected

SELECT * FROM kids;


KID_NAME
MONEY


Alice
.06

Beryl
.03

Carol
.08