SQL查询的正确合并

我有三个表

USERS

，

BOOKMARKS\u PRODUCTS

，

PRODUCTS

SELECT U.USER_NAME, U.USER_EMAIL, U.USER_PHONE, U.USER_AVATAR, U.ABOUT
FROM USERS AS U
WHERE U.USER_ID = '${user_id}'
SELECT B.PRODUCT_ID
FROM BOOKMARKS_PRODUCTS AS B
WHERE B.USER_ID = '${user_id}'
SELECT P.*
FROM PRODUCTS AS P
WHERE P.PRODUCT_ID = '${product_id}'

我需要从

USERS

表中，通过

ID

选择一个用户，在

BOOKMARKS\u PRODUCTS

表中找到它，从

PRODUCTS

表中，在

BOOKMARKS\u PRODUCTS

表中找到

PRODUCTS\u ID

字段中找到表中的所有产品

SELECT U.USER_NAME, U.USER_EMAIL, U.USER_PHONE, U.USER_AVATAR, U.ABOUT
FROM USERS AS U
WHERE U.USER_ID = '${user_id}'
SELECT B.PRODUCT_ID
FROM BOOKMARKS_PRODUCTS AS B
WHERE B.USER_ID = '${user_id}'
SELECT P.*
FROM PRODUCTS AS P
WHERE P.PRODUCT_ID = '${product_id}'

请帮助我正确地执行此操作。

您是否发现just join

select u.*,p.*,bp.* from  users u left join 
BOOKMARKS_PRODUCTS bp on u.USER_ID =bp.USER_ID 
left join PRODUCTS p on bp.PRODUCT_ID =p.PRODUCT_ID 

---

您可以在查询中使用JOIN从不同的表中获取数据

SELECT U.USER_NAME, U.USER_EMAIL, U.USER_PHONE, U.USER_AVATAR, U.ABOUT, B.PRODUCT_ID, P.* 
FROM USERS AS  U 
INNER JOIN BOOKMARKS_PRODUCTS AS B ON B.USER_ID = U.USER_ID -- OR '${user_id}'
INNER JOIN PRODUCTS AS P ON P.PRODUCT_ID = B.PRODUCT_ID -- OR '${product_id}'
WHERE U.USER_ID = '${user_id}'

更多参考