A nested table is a persistent SQL collection that is used as a list to hold elements of the same data type. It can also be created in the database and defined in a PL/SQL program. It is an unbounded collection and the user doesn't have to maintain the cell index. Oracle automatically assigns the cell index as 1 to the first cell and moves onwards incrementally. A nested table collection type initially starts off as a dense collection but it becomes sparse due to delete operations.
Note
A dense collection refers to a collection that is tightly populated which means no empty cells between the lower and upper indexes of the collection. A dense collection may become sparse by performing delete operations.
When a nested table is created as a schema object in the database, it can be referenced in a PL/SQL block as a variable parameter. A column of nested table types can be included in a table. An attribute of nested table types can exist in an object type. In a database schema, a nested...