I know that Yoast SEO plugin doesn't create any database table then why in wp_postmeta numbering of meta_id are not continuous?
Is it because of Yoast Plugin?
Also I want to know how its feature of automatic seo by default %%title%% in post works?
Because when I tried to use variable %%name%% with %%title%% in post type page but %%name%% appears as it is and %%title%% shows title of my page.
So I want that it takes authour name as per variable list of Yoast Plugin
It does not create tables, it stores data the "WordPress way" in the postmeta table, which is common to all WordPress functions. Because it's common to all WordPress functions, the ID's are going to be out of sequence for Yoast data, because it's going to be "commingled" with much other data that gets stored in that table.
As to your question about the %%name%% variable, it appears you are trying to use the variable inside your post title, which you cannot do. For it to work, you'd need to do something like so, in your Titles & Meta Settings:
%%title%% - by %%name%%
IMPORTANT UPDATE
This actually is a bug in the preview feature on the post (as of version 2.3.5, and up to and including version 3.0.7). The variable %%name%% is NOT getting parsed properly.
However, if you view the page itself, the variables are being parsed properly, including the %%name%% variable.
