Not Null Fields and Unmatched Number of Columns
I want to know what to do with the fields/columns that will not be filled with data and has a NOT NULL constraints? How should I approach this? I am new in this kind of task and my apologies for asking.


Remove the NOT NULL constraint on MySQL. You have columns that you don't need -- as evidenced by wanting to do this, and you're declaring them as necessary. There is nothing wrong with null. MySQL views NULL and NOT NULL as attributes of the type, and not constraints on the table. From the docs on the ALTER TABLE Syntax,

ALTER TABLE myTable
  MODIFY myCol INT NULL;


Where INT is the column type.

With PostgreSQL

For comparison, PostgreSQL has the more sane and standardized syntax,

ALTER [ COLUMN ] column_name { SET | DROP } NOT NULL


Which looks like this,

ALTER TABLE myTable
  ALTER COLUMN myColumn
  DROP NOT NULL;