]SAP transparent tables, structures, cluster introductions, and lookup table methods

Some people do not know how to find the transparent table of the screen field when they write the development function specification, let me introduce a more effective method:
Let's start with a brief introduction to the concept:
The following three types of tables are available in SAP: tranparent table,pools,cluster table.

Transparent table
Each transparent table has a corresponding physical table in the database. The name of the physical table is consistent with the name of the logical table definition in the data dictionary. The data processed in the object is stored in a transparent table. The database can be queried directly, and the ABAP staff would like to know the name of the table.

Storage table
Storage tables can be used to store control data (e.g., screen order, program parameters, or temporary data). Several storage
Tables can be combined into a single table library. The table library is consistent with a physical table library in the database. It contains all the groups
All records assigned to it by the library.

Cluster table
Continuous text, such as documents, can be stored in a cluster table. Several cluster tables can be combined into a single table cluster. For this type of table, several logical rows from different tables are combined into one physical record. This can implement an object to be stored or accessed by an object, accessing a table in a cluster on the premise that at least part of the keyword must match. Several cluster tables are stored in a corresponding table in the database.

Create a View structure
The structure of the generated view during the activity. The structure is used as an interface in the run time environment. Usually not displayed in the ABAP/4 dictionary.

Table
There are three types of tables in R/3:
Transparent table
Shared tables
Cluster table

Transparent table:
Transparent tables correspond to table one by one in the database, with the same table name, number of fields, and the definition of transparent tables in the ABAP Dictionary of field names relative to the database is independent, the defined table has the same structure as the table in the database. When the table is activated, the physical tables in the database are stored in the ABAP dictionary.

To share a table:
A shared table is a many-to-one relationship with tables in a database, with different table names, different field numbers, and different field names. Shared tables are a unique concept for SAP. In the database, all shared tables are stored in a table called the table pool. SAP uses shared tables to store system data.
Cluster table:
A cluster table is similar to a shared table. is also a many-to-one relationship. Most of the cluster tables are stored in a table called tables cluster, and the cluster table is used when some tables have a common PK, or when data is accessed synchronously.

The difference between a cluster table and a transparent table is that it is handled for a set of tables, and there is no difference between a single table and a transparent table, but multiple tables make up the cluster table and they are physically stored only once for the primary key, so the associated query to the cluster table can greatly improve the access speed.

A physical table definition is created in the database for the table definition stored in the ABAP Dictionary for Transpar ENT tables when the table is activated. The table definition is translated from the ABAP Dictionary to a definition of the particular database.

On the other hand, pooled tables and cluster tables is not created in the database. The data of these tables is stored in the corresponding table pool or table cluster. It is not a necessary to create indexes and technical settings for pooled and cluster tables.

Structure
The structure does not exist in the database data record. A structure is used to define an interface between programs or between programs and screens. The person who wrote the program should be easier to understand, structure is a predefined set of data formats, when the system from the database to query the data, it can be in the format required by the structure of the transfer into the structure. This storage is only based on memory or cache level and is not permanently stored.

Additional structure
An attached structure defines a subset of the fields that belong to other tables or structures, but as separate objects in remediation management. This is actually a reference to the structure field for other structures or tables.

In fact, in layman's terms, Cluster table is to put a bunch of data in a sequence in a certain "field" in a "special large", in the future to follow this particular rule to read.
Improve performance, save space, and piggyback to enhance security, which is what cluster table is for.

One way to look up a table in the interface is to use the processing list that is used by the data element, f1-> technology information

Examples are described below:
Enter Tcode:pa30, select a person, such as:

Select one of the fields, press F1,

Then select technical Infomation:

，

Double-click the data element:

Then select the processing list used:

When you click a list, you'll see what structures and tables refer to this data element, and you can see what it means by describing the field, which should be rare if you choose not to have a lot of criteria on your previous screen. You will soon be able to find the transparent table you want.

]SAP transparent tables, structures, cluster introductions, and lookup table methods