Compare SQL to PHP arrays

You can create and update with the first key at the same time.

INSERT INTO table(a,b,c)VALUES(1,2,3)
  ON DUPLICATE KEY UPDATE c=c+1;

https://dev.mysql.com/doc/refman/5.6/ja/insert-on-duplicate.html

If it already exists, you can update the update item with a date, etc., or overwrite the existing data.If there is no data update, it is also fast because it does not actually run.

I think it's easiest to select data and then compare it.

select date from table_name;

I will insert it after I get it as an array.

If you use insert into ... duplicate key update, it is easier to update the data by setting the update target to an update date or something like that.