COALESCE是否可以与VIEW一起正常使用？

Question

I have my view definition:

CREATE VIEW `view` AS
  SELECT a.id,
    COALESCE(COALESCE(b.name, c.name), a.name) AS name
  FROM a_table a
  LEFT JOIN b_table b on a.b_id = b.id
  LEFT JOIN c_table c on a.c_id = c.id

And after I'm updating a_table row with new name it doesn't get updated in my view . But if I change name to COALESCE(a.name, COALESCE(b.name, c.name)) AS name it works.

As I understand the reason is in COALESCE . It takes the first not null value and in my case it's b.name and gets updated only when b.name is updated.

Is there any option to updated the view when any of COALESCE values are changed?

Answer 1

COALESCE() works fine in views. It also takes multiple arguments, so I would suggest writing this as:

CREATE VIEW `view` AS
  SELECT a.id, COALESCE(b.name, c.name, a.name) AS name
  FROM a_table a LEFT JOIN
       b_table b 
       ON a.b_id = b.id LEFT JOIN
       c_table c 
       ON a.c_id = c.id;

Views are not "updated". They are SQL code that is plugged into queries when the view is reference. The data comes from the underlying tables.