Abap data dictionary pdf


 

The domain is a crucial concept in the ABAP Data Dictionary, because it defines the technical attributes of a table field such as data types, lengths, decimal. Data contained in this document serves informational purposes only. UNIT 2 Data Types in the ABAP. Dictionary. Lesson 1: Creating Domains and Data. ABAP/4 Dictionary. Q. What is a “DATA DICTIONARY”? A data dictionary is a central source of information for the data in a data management system. Its.

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Abap Data Dictionary Pdf

Changing Data Types and Lengths of Existing Fields. The ABAP Dictionary centrally describes and manages all the data definitions used. List of SAP tables (Customizing & Operational) – Sorted by Category Overview of Important SAP Tables ABAP / Data Dictionary Business Address Services. A data dictionary is a central source of information for the data in a information management system. Its main function is to support the creation.

No "logging" is performed even if the table has the Logging setting activated. When we run this transaction, if the instance profile parameter is not active, we will get a warning message. Evaluation of change logs From transaction SCU3 we can not only analyze the modification logs of tables, but we can also display a list of the dictionary tables that have the logging parameter set. Finally, it is very important to observe that this parameter should be only used in special cases and for short periods because it can create performance bottlenecks. Performance In order to improve the performance of table access, we can use two techniques: Indexes. This is described in a later section of this chapter. We have seen the positive effects of buffering in the previous sections. In the majority of occasions, the creation of indexes with good criteria will improve the performance of the database, but indexes have the disadvantage that it will make the database grow and will also impact the performance in database updates because every new update will have to update also the index. Likewise, the buffering technique can improve the performance of the accesses of a particular table, but it can also impact the general performance of the system. In conclusion, we see that performance is a complicated issue comprised of the balance between benefits and disadvantages and therefore requires continuous and periodic checking and tuning. Table Definition Modifications A very important aspect for the maintenance of the table in the dictionary is the updating or modification of the table definitions. There are some modifications that will not alter the structure of the table at the physical database level. We will deal in this section with those modifications that alter the structure.

If the data element is existing then you will be taken to the data element information screen in display mode and when you come back by pressing the BACK icon you will find the field type length and other information filled.

Click on the enter button if you want to create a new data element Enter the description of the data element. Note : You can also change the docu status with transaction SE You can also enter documentation for the data element.

Or press F9.

The text that you enter here will be displayed when you press F1 on the field. Click on the Yes button Enter the description for the domain in the Short text area Specify the data type in the Data Type box in the Format area Specify the field length Click on Save icon. In the resulting popup screen specify a Development Class. Activate the domain in the dictionary by clicking on the Generate icon on the application toolbar. Click on the BACK icon.

You will get a popup screen Specify a Development Class to save the object. Data in the tables of this class are not frequently changed Enter the Size Category. The Size Category defines the expected memory space required by the table on the database.

You have 0 to 4 size category to choose from for your tables. It defines the size of the table extents. Enter 1 in the Size Category. The value 1 in the size category indicates that the table is small. This parameter defined whether the all clients or selected clients should be logged. Specify at least one of the fields as the primary key and then click on Save icon to save the table and click on Generate icon to activate the table.

To create more fields in the table, click on the New Fields button on the application toolbar and repeat the above steps. This is how you can create a table. You can use the existing data elements by placing the cursor in the data element box and then pressing the F4 key. You can also reuse the domains that you create.

You can also create Data Elements with the existing domains. However, a structure does not correspond to an object in the database. The runtime object nametab collects this information in a table in a form, which is optional for application program access. In addition, it contains information about the table fields field name, position of the field in the table, data type, length, decimal places, reference field, check table, conversion routine, and so on.

The index ID may contain only letters and figures. The ID '0' is reserved for the primary index. Table names with fewer than 10 places are filled with underscores with the ID being added on at the end. The index ID is thus always located at positions This data exists in this copy in sorted form.

This sorting enables fast access to the data records of the table. In order that the remaining fields can also be read, that is, those fields not contained in the index, a pointer to the associated record of the actual table are included in the index. The operations, which the database utility executes for an object, are logged. The object log can be displayed from the database utility. In other words Views are a logical datasets which contain data extracted from a single table or multiple tables as a single entity.

The join conditions for the other view types must be obtained from existing foreign keys. Tables therefore can only be combined into a maintenance view or help view if they are linked to one another with foreign keys. The view will only include those entries that exist in both tables. The database views implement this type of joins. Outer joins. The table will include all the entries of all the tables in the view, even in the case that there are no entries in some tables.

The maintenance views implement this type of join. We can create four types of views in the system: Database views. They permit us to combine fields of several tables to be used in ABAP programs. Projection views.

They permit us to make a select a projection of a certain table. This type of view allows for hiding the complete content of a table to certain users. Maintenance views. These are views that allow a more simple maintenance of complex objects within the application. Help views. These are views that can be used in the search helps. These objects are also created in the dictionary. That is, we have to define the fields to be included in the view.

In the Selection Conditions tabstrip we have to enter the selection criteria for the data in the view. That is, we have to enter the conditions that must be met to select those records from the database.

The last tabstrip Maintenance Status is used to define whether the view is read only or if we allow it to be both read and update access. For the views that can be updated, we can also define whether data maintenance is allowed or not. Indexes We can define indexes in the dictionary to increase the performance for data access. These indexes are also created in the underlying database.

We can consider an index like a copy of the table, but only including the columns of the table that are defined by the index. The data of the indexes are classified according to the key defined for that index. Given this classification, accessing the data using the index reduces considerably the time to get and read that information, because the system can perform quick binary search using the index key.

We can access the definition and management of the indexes by selecting the menu option Goto Indexes or just clicking Indexes from the application toolbar.

Abap Data Dictionary

When we create and activate a table, the system creates the table and also an index that is known as "primary", where the key fields of the index matches the key fields of the table. This index can be used when we perform access to the table using key fields for the selection criteria. The remaining indexes are known as secondary indexes. The table indexes are identified by three characters.

The code "0" is reserved for the primary index. The customer indexes must begin with "Z" or "Y. Indexes can be unique or nonunique. A unique index defines which values of the key cannot be duplicated. An example of unique key is the primary key of the table. The nonunique indexes can accept duplicates values in the combination of the key fields. We can also decide whether the index will be created for some databases.

In some circumstances we might consider whether an index is recommended for a particular database; however, it could be not so good for other types of database engines. Fields within the WHERE clause set whether the index will be used for searching and accessing tables, although there are cases in which the system does not use any index for the search known as table full scan , because there are no criteria of the WHERE clause that match the defined indexes. When the structure of a table is modified, the system must perform an adjustment of the table indexes.

Tables with many updates should not have too many indexes defined because that could create some type of performance bottleneck.

We must also try to define table indexes that are somehow related, because the indiscriminate creation of indexes can mean that the database optimizer will not select the right index to use for the table access. They allow the user to enter values for an entry field by selecting them from a list of possible values.

The system shows the Possible Entries icon to the right of the field to indicate to the user that the field includes a search help. In order to use that help, we have two options: when in the field, clicking on the Possible Entries button, or just pressing F4. On many occasions, the list of possible entries of a field can be so large that it becomes necessary to perform additional restrictions for the search.

Data Dictionary

One of these restrictions is the number of entries to show, which by default is typically restricted to value " For instance, when we search for possible values on a date field, pressing the F4 key will show up a calendar.

Calendar as search help An easy way to create a field help, without the need to use the search helps, is the following: In the definition of a domain, in the tabstrip for the value range, we can enter the list of allowed values, a value range, or a reference table. In the first section we can enter individual values.

We can attach a descriptive text of the value that will appear when the user clicks on the Help button. We can also enter a value range, which also allows including a descriptive text. The other possibility is to include a table with reference values. When using this last option, we must perform some additional operations. Let's look at an example. The standard domain "BLART" does not have individual values or ranges but includes the reference table "T," which is a standard table for Document Types.

We are going to use the domain in the definition of the text elements. In the definition of the table we also must define a "foreign key" that allows us to relate the field to a reference table of possible values. To access to this screen, just click on the Foreign Keys button. The system detects that table T has been included in the data element used, and therefore it automatically proposes to use the related fields between the reference table T and the foreign key table BKPF.

Re-activate the domain when you are finished. Chapter 3 Exercises In the previous exercises, you established the basic objects to be used for a simplified payroll processing system. In addition to establishing the tables, data elements, and domains, you also established value tables for certain domains in order to ensure data integrity within the system. Now you will take this a step further by establishing appropriate foreign keys in the ABAP Dictionary.

Exercise 3. Exercise 4. Often times you must create a table and there is already a similar table on the database. So why reinvent the wheel? In the ABAP Workbench you can create a table then copy the elements of another table into your new table.

ABAP/4 Data Dictionary- Detail Description

Additionally it is possible to copy complete tables and then add fields. Step 3: Click the Copy icon on the application toolbar. Then click the green check mark. Step 4: Enter your package and change request when prompted. To improve the efficiency of this process, create a secondary index on the last name and first name fields. Create one index NAM that sort by last name, then by first name. Step 1: Create two fictitious health plans.

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