Oracle PL/SQL for DBAs

Collection Methods (Built-ins)

PL/SQL offers a number of built-in functions and procedures, known as collection methods , that let you obtain information about and modify the contents of collections. The following collection methods are available:

COUNT function

Returns the current number of elements in a collection.

DELETE procedure

Removes one or more elements from the collection. Reduces COUNT if the element is not already DELETEd. With VARRAYS, you can only delete the entire contents of the collection.

EXISTS function

Returns TRUE or FALSE to indicate whether the specified element exists.

EXTEND procedure

Increases the number of elements in a nested table or VARRAY. Increases COUNT.

FIRST, LAST functions

Return the smallest (FIRST) and largest (LAST) subscripts in use.

LIMIT function

Returns the maximum number of elements allowed in a VARRAY.

PRIOR, NEXT functions

Return the subscript immediately before (PRIOR) or after (NEXT) a specified subscript. You should always use PRIOR and NEXT to traverse a collection, especially if you are working with sparse (or potentially sparse) collections.

TRIM procedure

Removes collection elements from the end of the collection (highest defined subscript). Reduces COUNT if elements are not DELETEd.

These programs are referred to as methods because the syntax for using the collection built-ins is different from the normal syntax used to call procedures and functions. Collection methods employ a member method syntax that’s common in object-oriented ...