topic structure in Application Development and Automation Discussions

structure

Former Member — Wed, 16 Jan 2008 08:54:27 GMT

what is a structure, table type, view ,lock objects, match code?

only definitions plz?

thankyou.

Re: structure

FredericGirod — Wed, 16 Jan 2008 08:57:52 GMT

Structure is something without any data. It's only a list of field definition.

Re: structure

Former Member — Wed, 16 Jan 2008 09:01:29 GMT

Structures

A structure is a sequence of any other data types from the ABAP Dictionary, that is, data elements, structures, table types, or database tables. When you create a structure in the ABAP Dictionary, each component must have a name and a data type. In an ABAP program, you can use the TYPE addition to refer directly to a structure.

If you define a local data type in a program by referring to a structure as follows:

TYPES <t> TYPE <structure>.

Table Types

Table types are construction blueprints for internal tables that are stored in the ABAP Dictionary.

When you create a table type in the ABAP Dictionary, you specify the line type, access type, and key. The line type can be any data type from the ABAP Dictionary, that is, a data element, a structure, a table type, or the type of a database table. You can also enter a predefined Dictionary type directly as the line type, in the same way that you can with a domain.

Views:

There are 4 types views are avilable in SAP.

Database View - To club more than one table

Projection View - To hide fields in one table

Maintanance View - To maintain database records in table

Help View - To provide help for a fields (Same functionality as Search help. This is outdated)

View are improves perfromance in the following aspects

1. If you want to use more than two table in 'JOIN' condition better to use Views . It will improves performance of a program

2. If you want to use mutiple FOR ALL ENTRIES clause, better to club all SELECT statement in a view.

Lock Objects:

Lock objects are use in SAP to avoid the inconsistancy at the time of data is being insert/change into database.

SAP Provide three type of Lock objects.

Read Lock(Shared Locked)

protects read access to an object. The read lock allows other transactions read access but not write access to

the locked area of the table

Write Lock(exclusive lock)

protects write access to an object. The write lock allows other transactions neither read nor write access to

the locked area of the table.

Enhanced write lock (exclusive lock without cumulating)

works like a write lock except that the enhanced write lock also protects from further accesses from the

same transaction.

You can create a lock on a object of SAP thorugh transaction SE11 and enter any meaningful name start with EZ Example EZTEST_LOCK.

Use: you can see in almost all transaction when you are open an object in Change mode SAP could not allow to any other user to open the same object in change mode.

Example: in HR when we are enter a personal number in master data maintainance screen SAP can't allow to any other user to use same personal number for changes.

Technicaly:

When you create a lock object System automatically creat two function module.

1. ENQUEUE_<Lockobject name>. to insert the object in a queue.

2. DEQUEUE_<Lockobject name>. To remove the object is being queued through above FM.

Reward points if useful.

Re: structure

Former Member — Thu, 17 Jan 2008 05:36:06 GMT

hi,

Transparent Tables

are used to hold application data. Application data is the master data or transaction data used by an application.

Transparent tables are much more common than pooled or cluster tables. They are used to hold application data. Application data is the master data or transaction data used by an application

Table Pools and Pooled Tables

A pooled table in R/3 has a many-to-one relationship with a table in the database (see Figures 3.1 and 3.2). For one table in the database, there are many tables in the R/3 Data Dictionary.

Pooled tables are primarily used by SAP to hold customizing data.

Table Clusters and Cluster Tables

A cluster table is similar to a pooled table. It has a many-to-one relationship with a table in the database. Many cluster tables are stored in a single table in the database called a table cluster.

They are used to hold data from a few (approximately 2 to 10) very large tables.

They would be used when these tables have a part of their primary keys in common, and if the data in these tables are all accessed simultaneously.

lock objects

The SAP System synchronizes simultaneous access of several users to the same data records with a lock mechanism. When interactive transactions are programmed, locks are set and released by calling function modules (see Function Modules for Lock Requests). These function modules are automatically generated from the definition of lock objects in the ABAP Dictionary.

The tables in which data records should be locked with a lock request are defined in a lock object together with their key fields. When tables are selected, one table (the primary table) is first selected. Further tables (secondary tables) can also be added using foreign key relationships

views

A view can be used to combine the data distributed in several tables. Fields which are not required can be masked out, minimizing interfaces.

structures

Whereas data in tables is stored on the database, structures only contain data temporarily during program runtime.

Structures are defined (almost) exactly like tables; the only difference is that no database tables are generated from them. The same data elements and domains can be used in structures as in tables.

refer to the following site

http://help.sap.com/saphelp_40b/helpdata/en/4f/991f82446d11d189700000e8322d00/applet.htm

please rewrd points if helpful,

shylaja