您可以使用select ... where not exist (...)来确保不复制数据。假设列RestaurantName、UserName和RatingDate可以用作（伪）主键：

CREATE OR REPLACE PROCEDURE AddNewReview(
    pRestaurantName IN VARCHAR2 (100),
    pUserName IN VARCHAR2(100),
    pStars IN INT,
    pRatingDate IN DATE 
) AS 
BEGIN
    INSERT INTO newReview (RestaurantName, UserName, Stars, RatingDate)
    SELECT p.*
    FROM (
        SELECT pRestaurantName RestaurantName, 
            pUserName UserName, 
            pStars Stars, 
            pRatingDate RatingDate
        FROM DUAL
    ) p
    WHERE NOT EXISTS (
        SELECT 1
        FROM newReview r
        WHERE r.RestaurantName = p.RestaurantName 
          AND r.UserName = p.UserName 
          AND r.RatingDate = p.RatingDate
    )
END AddNewReview;

请注意，我重命名了IN参数，这样它们就不会与列名冲突。我还列出了插入的目标列。这两种变化都是好的做法。