3) INTERNAL TABLES

 INTERNAL TABLES:

• It is a temporary table created in application server to store multiple records temporarily.
• The life time and scope of the internal table is with in the program where it is created.
• It can be created either with header or without header.
• Header is like structure which can store single record, it is also called as wa(work area).
• The body of internal table is stored multiple records.
• To process the internal table data we need work area that is to append,reading,modifying,
• Deleting and for looping.

Append:

It adds the data from wa to end of internal table.

Loop-End Loop:

It is used for looping the internal table data from body to header.

Describe:

It contains the no of records in the internal table and stores the count values in the system field.

Sy-Tabix:

It is a system field ,which stores the current index position in the internal table.The index of the internal table starts from 1.

1) First method to create internal table.

Syntax:For declaring Internal table.

Data:begin of <IT> occurs <n>,

         Field1,

         Field2,

         -------,

         -------,

         End of <IT>.

<n> ranges from 0,1,2,3……..

Example program:

DATA:begin of emp occurs 0,

            Empno  type i,

            Ename  type c,

            Edesg   type c,

            End of emp.

     Emp-empno = 1.

     Emp-ename = ‘santu’

     Emp-edesg = ‘ceo;.

  Append emp.  ( “inserts one record into internal table body”)

Clear emp.     (“clears work area”)

begin of emp occurs 2,

            Empno  type i,

            Ename  type c,

            Edesg   type c,

            End of emp.

     Emp-empno = 1.

     Emp-ename = ‘santhosh’

     Emp-edesg = ‘team lead;

  Append emp.  ( “inserts one record into internal table body”)

Clear emp.     (“clears work area”)

2) Second method to create internal table.

Syntax:

Data:<internal table>like<existing structure>occurs<n>[with header line].

<n> ranges from 0,1,2,3….

By using above syntax we can create int.table with header line or without header line.

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•  It is not recommended to use the first and second methods for declaring internal tables,
•  Because in both syntaxes we need “occurs” statements which will do not static allocation memory.

STANDARD WAY OF DECLARING INTERNAL TABLE.

i)create the type declaration with the required fields.

Syntax:types:begin of <type name>,

                      Field 1,

                      Field 2,

                      --------

                      End of <internal table>.

ii)create the internal table work area and body based on data declaration.

Data:wa type <internal table>

          Itab type standard table of <internal table>

                          OR

 Data:wa type <internal table>

          Itab type standard table of wa.

                          OR

 Data: Itab type standard table of <internal table>

           wa like line of Itab.

        

Example:

Types:begin of ty_emp,

            Eno      type zeno, 

            Ename  type zename,                                                               

            Edesg   type zedesg,

            End of ty_emp.

 Data:wa   type ty_emp,

         Itab type standard table of ty_emp.

 Note:(we can refer from custom data elements or table data elements etc.)

To refresh the contents of internal table we can use

i)Clear

ii)Refresh

iii)Free

Clear:      It can clears the contents of int.table.

Refresh: Refreshes the contents of the int.table.

Free:       Clears the contents as well as deallocate the memory that is gets the memory to the initial screen

  

To delete the duplicate records from int.table we use syntax “delete adjacent duplicates”

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Internal table creation: