PL/SQL TABLES:


        a) Objects of type TABLE are called PL/SQL tables.
        b) They are modeled as database tables, but are not same.
        c) PL/SQL tables use a Primary key to give array like access to Rows.

     Things To Note:
     --------------
              i) It is similar to an Array.
             ii) It shouls contains two components.
                        * A PRIMARY KEY of datatype BINARY_INTEGER, that Indexes the PL/SQL Table.
                        * A Column of a scalar or Record datatyoe which stores the PL/SQL TABLE elements.
            iii) It can increase dynamically as it is unconstrained.

 CREATING A PL/SQL TABLE:
=========================

         a) There are two steps involved in creating a PL/SQL Table.
                   -> Declare a TABLE Datatype.
                   -> Declare a Variable of that Datatype.

                         Syntax:
                               TYPE TypeName IS TABLE OF
                               { ColumnType | Variable%TYPE
                 | Table.Column%TYPE} [NOT NULL]
                [INDEX BY BINARY_INTEGER];
                               
                               Identifier TypeName;
                       
                         Example:
                               TYPE Ename_Table_TYOE IS TABLE OF Emp.Ename%TYPE INDEX BY BINARY INTEGER;
                               EnameTable Ename_Table_Type;

PL/SQL TABLE STRUCTURE:
           
            PRIMARY KEY              COLUMN
            
                      1                              SATISH
                      2                              RAJ
                      3                              KRISHNA
                 
               BINARY_INTEGER             SCALAR
   
         a) The number of rows in PL/SQL table can increase dynamically, Hence a PL/SQL table can grow as new rows are added.
         b) PL/SQL tables can have one column and a PRIMARY KEY, neither of which can be named.
         c) The column can belong to any scalar or record datatype, but the PRIMARY KEY must belong to Typr BINARY_INTEGER.
         d) We cannot initialize a PL/SQL table in its declaration.

REFERENCING A PL/SQL TABLE:


         Syntax:
                PL/SQL_Table_Name(Primary_Key_Value);
         a) Primary_Key_Value belongs to type BINARY_INTEGER.
         b) The Primary Key value can be negative Indexing need not start with 1.
         c) The Methods that make PL/SQL Tables easier to use are

                * EXISTS(n)   -> Returns TRUE if the nth element in a PL/SQL table exists.
                * COUNT       -> Returns the number of elements that PL/SQL TABLE currently contains.
                * FIRST and
            LAST  -> Returns the FIRST and Last index numbers in PL/SQL Table. Returns NULL if the PL/SQL table is empty.
                * Prior(n)    -> Returns the Index number that preceeds index n in a PL/SQL Table.
                * NEXT(n)     -> Returns the Index number taht succeeds Index n in a PL/SQL Table.
                * EXTEND(n.i) -> It increases the size of a PL/SQL Table.
                     
                                   i) It appends one NULL element to a PL/SQL Table.
                                  ii) EXTEND(n) appends n NULL elements into a PL/SQL table.
                                 iii) EXTEND(n.i) appends n copies of the ith element to a PL/SQL Table.
                * TRIM       -> It removes one element from the end of a PL/SQL Table.
                * DELETE     -> It removes all elements from a PL/SQL Table.
               
                        DELETE(n), DELET(m,n)
         d) To Reference PL/SQL Table of Records we use
                        -> Table(index).Field
            Example:
                      SQL > DECLARE
                                   TYPE Dept_Table_Type IS TABLE OF Dept.DName%TYPE INDEX BY BINARY_INTEGER;
                                   My_Dept_Table Dept_Table_Type;
                                   V_Count NUMBER(2);
                            BEGIN
                                   SELECT COUNT(*) INTO V_Count FROM DEPT;
                                   FOR MyIndex IN 1...V_Count
                                   LOOP
                                       SELECT Dname INTO My_Dept_Table(MyIndex) FROM DEPT WHERE Deptno=MyIndex*10;
                                   END LOOP;
                                   FOR MyIndex IN 1....V_Count
                                   LOOP
                                       DBMS_OUTPUT_PUTLINE(My_Dept_Table(MyIndex));
                                   ENDLOOP;
                            END;

                      SQL > DECLARE
                                   TYPE Dept_Table_Type IS TABLE OF Dept%ROWTYPE INDEX BY BINARY_INTEGER;
                                   My_Dept_Table Dept_Table_Type;
                                   V_Count NUMBER(2);
                            BEGIN
                                   SELECT COUNT(*) INTO V_Count FROM DEPT;
                                   FOR MyIndex IN 1...V_Count
                                   LOOP
                                       SELECT *INTO My_Dept_Table(MyIndex) FROM DEPT WHERE Deptno=MyIndex*10;
                                   END LOOP;
                                   FOR MyIndex IN 1....V_Count
                                   LOOP
                                       DBMS_OUTPUT_PUTLINE('Department NUmber'||My_Dept_Table(MyIndex).DeptNO||'Department Name'||My_Dept_Table(MyIndex).DeptName ||'Department Location'||My_Dept_Table(MyIndex).LOC);
                                   ENDLOOP;
                            END;