Associative arrays in Oracle are similar to conventional lists in other programming languages. An associative array is an unbounded array of cells and always defined in the declarative section of a PL/SQL program. While a cell is identified by an index of number or string type, it can hold a value of a scalar data type or user-defined composite type.
The syntax to declare an associative array in a PL/SQL block is as follows:
TYPE [COLL NAME] IS TABLE OF [ELEMENT DATA TYPE] NOT NULL INDEX BY [INDEX DATA TYPE]
In the syntax, the [INDEX DATA TYPE] signifies the data type of an array subscript. It can be BINARY_INTEGER, PLS_INTEGER, POSITIVE, NATURAL, SIGNTYPE, or VARCHAR2. The data types that are not supported as index types are RAW, NUMBER, LONG-RAW, ROWID, and CHAR.
The [ELEMENT DATA TYPE] can be one of the following:
PL/SQL scalar data type:
NUMBER(along with its subtypes),VARCHAR2(and its subtypes),DATE,BLOB,CLOB, orBOOLEANInferred data: The data type inherited from...