Is View Updatate is possible ?

Not all of them Some views are updatable eg single table view with all the fields or mandatory fields Examples of non-updatable views are views which are joins, views that contain aggregate functions(such as MIN), and views that have GROUP BY clause.

What does the SQLCODE -818 pertain to?

This is generated when the consistency tokens in the DBRM and the load module are different.

What is SQL-811?

SELECT statement has resulted in retrieval of more than one row.

What is SQLCODE -922 ?

Authorization failure

What is the difference between Primary Key & Unique index ?

Primary : a relational database constraint Primary key consists of one or more columns that uniquely identify a row in the table For a normalized relation, there is one designated primary key 

Unique index: a physical object that stores only unique values There can be one or more unique indexes on a table.