Updating a record in sql
PL/SQL nested tables are like one-dimensional arrays.
You can model multi-dimensional arrays by creating nested tables whose elements are also nested tables.
Ambrose Bierce Many programming techniques use collection types such as arrays, bags, lists, nested tables, sets, and trees.
Nested tables and varrays can also be attributes of object types.
You must update or retrieve all elements of the varray at the same time, which is most appropriate when performing some operation on all the elements at once.
But you might find it impractical to store and retrieve large numbers of elements this way.
The most efficient way to pass collections to and from the database server is to use anonymous PL/SQL blocks to bulk-bind input and output host arrays to associative arrays.
Varrays are a good choice when the number of elements is known in advance, and when the elements are usually all accessed in sequence.