When we start a database in oracle this contains many objects which includes tables, views,indexes, packages, procedures, functions, triggers,types,sequences etc.
Tables are the basic units of the databse, which is used to store data.
INSERT statement is used to insert a single record or multiple records into a table.
UPDATE statement is used to update the data inside the table
ALTER is to add a column, modify a column, drop a column, rename a column or rename a table