Question

以下代码为：

--Code Created by Michael Berkowski
create table dvd (
   dvd_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY
  );
INSERT INTO dvd VALUES (1),(2),(3),(4);

CREATE TABLE dvd_price (
   dvd_price_id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
   dvd_id INT NOT NULL,
   rental_amount INT,
   time_rented_for VARCHAR(10) 
);

INSERT INTO dvd_price (dvd_id, rental_amount, time_rented_for)
  SELECT
    dvd_id,
    2 AS rental_amount,
    rental_period
  FROM
    dvd
    CROSS JOIN (

      -- This is where I'm having issues
      SELECT (CASE dvd.dvd_id
                WHEN dvd.dvd_id = 1
                THEN '1-Day'
                ELSE '3-Day'
              END) AS rental_period
  ) rental_periods

为什么我不能在CROSS JOIN之后做一个CASE语句，我该如何解决这个问题呢？我在字段列表中收到错误“未知表'dvd'：”，有什么更好的方式来写这个？

Answer 1

尝试这种方式：

INSERT INTO dvd_price (dvd_id, rental_amount, time_rented_for)
  SELECT
    dvd_id,
    2 AS rental_amount,
    CASE dvd.dvd_id
                WHEN dvd.dvd_id = 1
                THEN '1-Day'
                ELSE '3-Day'
              END
  FROM
    dvd

Mysql INSERT INTO使用SELECT和INNER JOIN WITH CASE

1 个答案: