如何在Oracle上透视此表？

CREATE TABLE sales (
    product_id NUMBER,
    sale_date DATE,
    quantity NUMBER
);

SELECT *
FROM (
    SELECT product_id, sale_date, quantity
    FROM sales
    WHERE sale_date >= ADD_MONTHS(SYSDATE, -12) -- 只选择最近一年的数据
)
PIVOT (
    SUM(quantity) FOR sale_date IN ('01-JAN-2022', '01-FEB-2022', '01-MAR-2022', ...)
)

DECLARE
    v_sql VARCHAR2(4000);
BEGIN
    v_sql := 'SELECT product_id, ';
    
    FOR rec IN (
        SELECT DISTINCT TO_CHAR(sale_date, 'DD-MON-YYYY') AS sale_date
        FROM sales
        WHERE sale_date >= ADD_MONTHS(SYSDATE, -12)
        ORDER BY sale_date
    ) LOOP
        v_sql := v_sql || 'MAX(CASE WHEN sale_date = ''' || rec.sale_date || ''' THEN quantity END) AS "' || rec.sale_date || '", ';
    END LOOP;
    
    v_sql := SUBSTR(v_sql, 1, LENGTH(v_sql) - 2) || ' FROM sales WHERE sale_date >= ADD_MONTHS(SYSDATE, -12) GROUP BY product_id';
    
    EXECUTE IMMEDIATE v_sql;
END;
/