Question

我有一个添加请求：

INSERT INTO LIKES_PRODUCTS AS L (L.USER_ID, L.PRODUCT_ID) VALUES('7', '1')

请求表中的行数：

SELECT COUNT(L.USER_ID) AS LIKES FROM LIKES_PRODUCTS AS L

是否可以将它们组合成一个查询，以便首先进行添加，然后仅对表中的行进行计数？

Answer 1

您可以使用data modifying CTE

with new_row as (
  insert into likes_products (user_id, product_id)
  values (7,1)
)
select count(user_id) as likes
from likes_products;

但是，最后的select看不到前CTE的影响。如果您总是插入一行，则只需在选择中插入count(user_id) + 1。另一种选择是返回插入的行并将其添加到计数中：

with new_rows as (
  insert into likes_products (user_id, product_id)
  values (7,1),(8,2)
  returning *
)
select count(user_id) + (select count(*) from new_rows) as likes
from likes_products;

如何将选择并插入到SQL中

1 个答案: