How do I add a new column to MySQL via phpMyAdmin?

Coming from years of experience with MS SQL Server I though it would be easy to add a simple nullable integer column to a MySQL database table using phpMyAdmin. I simply found the part of the UI that most resembled the part of SSMS where a new column is added to a table in SQL Server, clicked add column, entered a name, selected int, and null for default value.

The table itself is a posts table created by WordPress. When I click save I get an error saying

ALTER TABLE ‘wp_posts’ ADD ‘acserp’ INT NULL DEFAULT NULL AFTER ‘comment_count’;

MySQL said: Documentation

#1067 – Invalid default value for ‘post_date’

I really don’t see what adding an integer column has to do the the post_date column unless some row in the posts table has an invalid value for post_date and mySQL does some sort of checks to make sure that noting is wrong with the rest of the table before adding anything.