Data Dictionary

[Former Member]

Please let me know each n every single thing about data dictionary n also the steps to create tables. The version I m working with is ECC6.0

Edited by: aYu on Jan 8, 2008 5:53 AM

[Former Member]

The DDIC is nothing but the ABAP Dictionary. The ABAP Dictionary centrally describes and manages all the data definitions used in the system.

Data types

Data types are the actual type definitions in the ABAP Dictionary. They allow you to define elementary types, reference types, and complex types that are visible globally in the system. The data types of database tables are a subset of all possible types, namely flat structures.

Data Elements

Data elements in the ABAP Dictionary describe individual fields. They are the smallest indivisible units of the complex types described below, and are used to specify the types of columns in the database. Data elements can be elementary types or reference types.

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.

Type Groups

Before Release 4.5A, it was not possible to define standalone types in the ABAP Dictionary to which you could refer using a TYPE addition in an ABAP program. It was only possible to refer SAP AG BC - ABAP Programming

Data Types in the ABAP Dictionary to flat structures. Structures in programs corresponded to the structures of database tables or structures in the ABAP Dictionary. In ABAP programs, you could only refer to database tables and structures in the ABAP Dictionary using LIKE. It was, however, possible to refer to individual components of the Dictionary type. Complex local data types such as internal tables or deep structures had no equivalent in the ABAP Dictionary. The solution to this from Release 3.0 onwards was to use type groups. Type groups were based on the include technique, and allowed you to store any type definitions globally in the Dictionary by defining them using TYPES statements.

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.

You have to use these function module in your program.

Search Helps:

These are two types.

Elementary n Collective.

1) Elementary search helps describe a search path. The elementary search help must define where the data of the hit list should be read from (selection method), how the exchange of values between the screen template and selection method is implemented (interface of the search help) and how the online input help should be defined (online behavior of the search help).

2) Collective search helps combine several elementary search helps. A collective search help thus can offer several alternative search paths.

3)An elementary search help defines the standard flow of an input help.

4) A collective search help combines several elementary search helps. The user can thus choose one of several alternative search paths with a collective search help.

5)A collective search help comprises several elementary search helps. It combines all the search paths that are meaningful for a field.

6)Both elementary search helps and other search helps can be included in a collective search help. If other collective search helps are contained in a collective search help, they are expanded to the level of the elementary search helps when the input help is called.

See the below link to understand this completely:

http://help.sap.com/saphelp_nw2004s/helpdata/en/cf/21ee93446011d189700000e8322d00/frameset.htm

Rewards if useful

Edited by: Sravan Prakash.V on Jan 8, 2008 10:23 AM

[Former Member]

Creating a Table: T.Code SE11

Steps to Creating domains, Data Elements, Tables

To give you the steps for creating table:.

There are two approach in creating a table.

1. Bottom-up approach

2. Top-down approach.

Both are valid and you can choose which approach is suitable for you. I always use the bottom-up approach. Here are the steps to create the tables with this approach.

1. SE11 will take you to the DDIC and enter the name of the new table to be created. Let us say Zname. Click create.

2. Enter the short discription of the table and enter the field of the table. If it is primary key and you have to check the box.

3. Enter the data element and double click it, you will be asked to save and will take you to data element discription page. Enter the short discription of the data element and enter the information of domain like the length of field and type of field.

4. If you wanted to use the existing domain then its fine, or else, you have to create one. Enter the domain name in the data element page and double click it. Page will ask to save and jump to domain creation page.

5. In the domain page, you have to save the information which you have already given in the data elements page and check it. Before going to data element page, you have to activate the domain.

6. Go to data element page and save, check and activate.

7. Go to main table page and save, check, and activate.

8. Also, you have to save the technical settings of the table.

The table is now ready for operation. You can use it in your program or you can use it to enter information.

Check table: It is the table which will have all the information about the Foreign keys which are the primary keys in the check table.

It can be created by creating the foreign key from the main table. Click foreign key in the main table and it will take you to a page which will ask for table name and field to which foreign key relation has to be associated. Enter the information and you can create the check table automatically.

SM30 is used for maintenance of the table, that is to realease the errors occured during the creation of the table

Reward points if useful.

[Former Member]

Data Dictionary

ABAP 4 data dictionary describes the logical structures of the objects used in application development and shows how they are mapped to the underlying relational database in tables/views.

Different types of data dictionary objects

tables, structures, views, domains, data elements, lock objects, Matchcode objects.

Views

A view is a logical view on one or more tables. A view on one or more tables i.e, the data from a view is not actually physically stored instead being derived from one or more tables. A view can be used to summarize data which is distributed among several tables

- Database View (SE11)

Database views are implement an inner join, that is, only records of the primary table (selected via the join operation) for which the corresponding records of the secondary tables also exist are fetched. Inconsistencies between primary and secondary table could, therefore, lead to a reduced selection set. In database views, the join conditions can be formulated using equality relationships between any base fields. In the other types of view, they must be taken from existing foreign keys. That is, tables can only be collected in a maintenance or help view if they are linked to one another via foreign keys.

- Help View ( SE54)

Help views are used to output additional information when the online help system is called. When the F4 button is pressed for a screen field, a check is first made on whether a matchcode is defined for this field. If this is not the case, the help view is displayed in which the check table of the field is the primary table. Thus, for each table no more than one help view can be created, that is, a table can only be primary table in at most one help view.

- Projection View

Projection views are used to suppress or mask certain fields in a table (projection), thus minimizing the number of interfaces. This means that only the data that is actually required is exchanged when the database is accessed. A projection view can draw upon only one table. Selection conditions cannot be specified for projection views.

- Maintenance View ( SE54 )

Maintenance views enable a business-oriented approach to looking at data, while at the same time, making it possible to maintain the data involved. Data from several tables can be summarized in a maintenance view and maintained collectively via this view. That is, the data is entered via the view and then distributed to the underlying tables by the system.

Domains:Domain is the central object for describing the technical characteristics of an attribute of an business objects. It describes the value range of the field.

Data Element: It is used to describe the semantic definition of the table fields like description the field. Data element describes how a field can be displayed to end-user.

Matchcode objects

A matchcode is a tool to search for data records in the system. Matchcodes are an efficient and user-friendly search aid for cases where the key of a record is unknown. It consists of two stages one is Match code object and the other is Matchcode ID. A matchcode object describes the set of all possible search paths for a search term. Matchcode ID describes a special search path for a search term.

There are the following types of search helps:

o Elementary search helps implement a search path for determining to possible entries.

o Collective search helps contain several elementary search helps. collective search help therefore provides several alternative sea paths for possible entries.

o Append search helps can be used to enhance collective search help delivered by SAP with customer-specific search paths without requiring a modification.

LOCK OBJECTS

A lock object is a virtual link of several SAP tables which is used to synchronize simultaneous access by two users to the same set of data

Locks are requested and released in the programming of online transactions by calling certain function modules which are automatically generated from the definition of the lock objects. These lock objects

must be explicitly created in the ABAP Dictionary.

To set locks, you must perform the following steps:

1. You must define a lock object in the ABAP Dictionary. The name of the lock object should begin with E.

2. The function modules for requesting and releasing locks which are created automatically when the lock object is activated must be linked to the programming of the relevant online transactions.

Check these links...It is very very useful one.

https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/library/abap/how%20to%20im...

Check this link for ABAP Program to Create Data Dictionary Objects

https://www.sdn.sap.com/irj/sdn/go/portal/prtroot/docs/library/uuid/775bc73e-0e01-0010-79a0-e9d0243e...

Table creation

1.Go to SE11 Transaction.

2.Give Table name starts with Z or Y letter -->click create.

3.Give short description & Delivery class as "A", & Data Browser as "Display/Maintenace Allowed".

4.Click Field tab,give MANDT in field & Data element, click primary key check box & initial values and give Enter on dataelement.

5. Give field name which u want, this s primary key field. so click key check box & initial values, give data element name starts with Z or Y double click on that data element,popwindow wil come, in that click yes, give ur package name>save, it wil ask to create data element, so click yes.Then give short description, in Data type tab click we can choose either Domain or Buil-in type.If u want domain,select domain give any name starts with Z or Y, double click on that>yes >Save.It wil ask to Create domain>yes. Give short desc, give required data type, No.Chars & Output length -->Save --> Activate.

Note: We can use old domain values or we can create new domains.

6. In data element page, click Field label tab. Give short, medium, Long & Heading values >save>Activate.

7.Go to main table page, Give other fields which u want, here no need to give primary key. Do the same steps as told previously.

7.Go to Technical Setting at the top of the page.Give the Data class "APPL0". Select Size category as 0 or anything which u want -->click Save button --> Go back.

8.Activate the main table -->Save.

9.Go to Utilities -->Table contents --> Create Entries. Then Create the Records.

http://help.sap.com/saphelp_nw04/helpdata/en/cf/21eb6e446011d189700000e8322d00/frameset.htm

Regards,

Maha

[Former Member]

Check the following link

http://www.sapbrainsonline.com/TUTORIALS/TECHNICAL/dictionary_tutorial.html

[Former Member]

Hi,

You can refer to the document:

http://help.sap.com/saphelp_webas620/helpdata/en/cf/21ea31446011d189700000e8322d00/content.htm

Regards,

Renjith Michael.

[Former Member]

Steps to Creating domains, Data Elements, Tables

To give you the steps for creating table:.

There are two approach in creating a table.

1. Bottom-up approach

2. Top-down approach.

Both are valid and you can choose which approach is suitable for you. I always use the bottom-up approach. Here are the steps to create the tables with this approach.

1. SE11 will take you to the DDIC and enter the name of the new table to be created. Let us say Zname. Click create.

2. Enter the short discription of the table and enter the field of the table. If it is primary key and you have to check the box.

3. Enter the data element and double click it, you will be asked to save and will take you to data element discription page. Enter the short discription of the data element and enter the information of domain like the length of field and type of field.

4. If you wanted to use the existing domain then its fine, or else, you have to create one. Enter the domain name in the data element page and double click it. Page will ask to save and jump to domain creation page.

5. In the domain page, you have to save the information which you have already given in the data elements page and check it. Before going to data element page, you have to activate the domain.

6. Go to data element page and save, check and activate.

7. Go to main table page and save, check, and activate.

8. Also, you have to save the technical settings of the table.

The table is now ready for operation. You can use it in your program or you can use it to enter information.

Check table: It is the table which will have all the information about the Foreign keys which are the primary keys in the check table.

It can be created by creating the foreign key from the main table. Click foreign key in the main table and it will take you to a page which will ask for table name and field to which foreign key relation has to be associated. Enter the information and you can create the check table automatically.

SM30 is used for maintenance of the table, that is to realease the errors occured during the creation of the table.

Well, this is the information I have.

[Former Member]

Hi,

plz gimme your mail id so thati can send you the material.

regards,

srikanth tulasi.

[Former Member]

Hi,

pls go thru the steps to create the tables

1.goto se11

2.enter the table name

3.click create

4.give the description

5.in delivery and maintainace give A in delivery class

6.press enter

7.in fields give the fields watever u need..

8.save it and activate.

Here are the summarized steps for Table Maintenance

1) Go to SE11

2) In Delivery and Maintenance TAB

i) Delivery Class as A ( most of the times)

ii) Data Browser/Table View Maint. as "Display/Maintenance Allowed"

3) Enter the required fields.

4) Goto Technical Settings.Enter the appropriate data

5) Then go to Utilities-->Table Maintenance Generator

i) Enter the Authorization Group (Varies from project to project...when no authorization required give &NC& )

ii)Function Group as "Table Name"

iii)Package varies from project to project

iv)Maintenance Type as "One Step"

a)Give overview Screen Number (Your own number..but remember)

b)Single Screen "Any number"(it can be 0 also)

6) Then click on the white color create button on menu bar(Create)

7) To view the maintenance Screen Transaction is SM30(There you need to give the table name)

😎 If you want to change the description of the fields,alignment,mandatory,greying the fields,Validations and many more

goto SE51 enter program name as "SAPL(TABLE NAME) EX:SAPLZH116 and enter the screen number what you gave in the step 5,iv,a.

9)If u want to have a transaction to table maintenance

a)Go to SE93

b)Choose "Transaction with Parameters" Radio button

c)Give the Package Name which is given in 5,iii

d)Give transaction as SM30

e)Choose Skip Initial Screen

f)In GUI Support Choose all the three options

g) In the default values Tab

Name of the Screen Field Value

UPDATE X

VIEWNAME (Enter Table Name)

Save and Activate

Regards,

Ari

[Former Member]

Hi,

DATA DICTIONARY

questions and their answers

1. What are the layers of data descriptions in R/3?

The external layer

The ABAP/4 layer

The database layer

2. Define external layer.

The external layer is the plane at which the user sees and interacts With the data, that is, the data format in the user interface. This data Format is independent of the database system used.

3. Define ABAP/4 layer?

The ABAP/4 layer describes the data formats used by the ABAP/4 processor.

4. Define Database layer ?

The database layer describes the data formats used in the database.

5. What is a Data Class?

The Data class determines in which table space the table is stored when it is created in the database.

6. What is a Size Category?

The Size category describes the probable space requirement of the table in the database.

7. How Many types of size categories and data classes are there?

There are five size categories (0-4) and 11 data classes, only three of which are appropriate for application tables:

APPL0 - Master data (data frequently accessed but rarely updated)

APPL1 - Transaction data (data that is changed frequently)

APPL2 - Organizational data (customizing data that is entered when system is Configured and then rarely changed)

The other two types are:

USR

USR1 - Intended for customers own developments

8. What are control tables?

The values specified for the size category and data class are mapped to database-specific values via control tables.

9. What is the function of the transport system and workbench organizer?

The function of the transport system and the Workbench Organizer is to manage any changes made to objects of the ABAP/4 Development Workbench and to transport these changes between different SAP systems.

10. What is a table pool?

A table pool (or pool) is used to combine several logical tables in the

ABAP/4 Dictionary. The definition of a pool consists of at least two keys

Fields and a long argument field (VARDATA).

11. What are pooled tables?

These are logical tables which must be assigned to a table pool when they are defined. Pooled tables can be used to store control data (such as Screen sequences or program parameters).

12. What is a table cluster?

A table cluster combines several logical tables in the ABAP/4 Dictionary. Several logical rows from different cluster tables are brought together in a single physical record. The records from the cluster tables assigned to a cluster are thus stored in a single common table in the database.

13. How can we access the correction and transport system?

Each time you create a new object or change an existing object in the ABAP/4 Dictionary, you branch automatically to the Workbench Organizer or correction and transport system.

14. Which objects are independent transport objects?

Domains, Data elements, Tables, Technical settings for tables, Secondary indexes for transparent tables, Structures, Views, Match code objects, Match code IDs,Lock objects.

15. How is conversion of data types done between ABAP/4 & DB layer?

Conversion between ABAP/4 data types and the database layer is done within the database interface.

16. How is conversion of data types done between ABAP/4 & external level?

Conversion between the external layer and the ABAP/4 layer is done in the SAP dialog manager DYNP.

17. What are the Data types of the external layer?

ACCP, CHAR, CLNT, CUKY, CURR, DATS, DEC, FLTP, INT1, INT2, INT4, LANG, LCHR, LRAW, NUMC, PREC, QUAN, RAW, TIMS, UNIT, VARC.

18. What are the Data types of the ABAP/4 layer?

Possible ABAP/4 data types:

C: Character.

😧 Date, format YYYYMMDD.

F: Floating-point number in DOUBLE PRECISION (8 bytes).

I: Integer.

N: Numerical character string of arbitrary length.

P: Amount or counter field (packed; implementation depends on hardware platform).

S: Time stamp YYYYMMDDHHMMSS.

T: Time of day HHMMSS.

V: Character string of variable length, length is given in the first two bytes.

X: Hexadecimal (binary) storage.

19. How can we set the tablespaces and extent sizes ?

You can specify the extent sizes and the tablespace (physical storage area in the database) in which a transparent table is to be stored by setting the size category and data class.

20. What is the function of the correction system?

The correction system manages changes to internal system components,

such as objects of the ABAP/4 Dictionary.

21. What are local objects?

Local objects (Dev class $TMP) are independent of correction and transport system.

22. What is a Development class?

Related objects from the ABAP/4 repository are assigned to the same development class.This enables you to correct and transport related objects as a unit.

23. What is a data dictionary ?

Data dictionary is a central source of data in a data management system. Its main function is to support the creation and management of data definitions. It has details about

What data is contained ?

What are the attributes of the data ?

What is the relationship existing between the various data elements ?

23. What functions does a data dictionary perform ?

In a data management system, the principal functions performed by the data dictionary are

- Management of data definitions

- Provision of information for evaluation

- Support for software development

- Support form documentation

- Ensuring that the data definitions are flexible and up-to-date.

24. What are the features of ABAP/4 Dictionary ?

The most important features are :

- Integrated to ABAP/4 Development Workbench

- Active in the runtime environment

25. What are the uses of the information in the Data dictionary ?

The following information is directly taken from the Data dictionary :

- Information on fields displayed with F1 help

- Possible entries for fields displayed with F4 help

- Matchcode and help views search utitlities.

26.What are the basic objects of the data dictionary ?

- Tables

- Domains

- Data elements

- Structures

- Foreign keys

27. What are the aggregate objects in the data dictionary?

- Views

- Matchcodes

- Lock objects

28.In the ABAP/4 Dictionary Tables can be defined independent of the underlying database (T/F)

True

29. ABAP/4 Dictionary contains the Logical _ (Logical/Physical) definition of the table.

30. A field containing currency amounts (data type CURR) must be assigned to a reference table and a reference field. Explain.

• As a reference table, a system table containing all the valid currencies is assigned or any other table which contains a field with the currency key format. This field is called as reference field. The assignment of the field containing currency amounts to the reference field is made at runtime. The value in the reference field determines the currency of the amount.

31. A field containing quantity amounts (data type QUAN) must be assigned to a reference table and a reference field. Explain.

• As a reference table, a system table containing all the valid quantity units is assigned or any other table which contains a field with the format for quantity units (data type UNIT). This field is called as reference field. The assignment of the field containing quantity amounts to the reference field is made at runtime. The value in the reference field determines the quantity unit of the amount.

32. What is the significance of Technical settings (specified while creating a table in the data dictionary) ?

By specifying technical settings we can control how database tables are created in the database. The technical settings allows us to

- optimize storage space requiremnets

- table access behaviour

- buffering required

- changes to entries logged

33.What is a Table attribute ?

The table attributes determine who is responsible for maintaining a table and which types of access are allowed for the table. The most important table attributes are:

a. Delivery class

b. Table maintenance allowed

c. Activation type.

34. What is the significance of Delivery Class ?

The delivery class controls the degree to which the SAP or the customer is responsible for table maintenance

• whether SAP provides the table with or without contents.

• determines the table type.

• determines how the table behaves when it is first installed, at upgrade, when it is transported, and when a client copy is performed.

35. What is the maximum number of structures that can be included in a table or structure

- Nine.

36. What are the two methods of modifying Sap standard tables ?

- Append Structures and

- Customizing Includes.

39. What is the difference between a Substructure and an Append Structure ?

In case of a substructure, the reference originates in the table itself, in the forma of a statement .include... .

In case of an append structure, the table itself remains unchanged and the refrence originates in the append structure.

40. To how many tables can an append structure be assigned ?

One.

41. If a table that is to be extended contains a long field, we cannot use append structures. Why?

Long fields in a table must always be located in the end, as the last field of the table. If a table has an append structure the append line must also be on the last field of the table.

42.Can we include customizing include or an append structure with Pooled or Cluster tables ?

No.

43. What are the two ways for restricting the value range for a domain ?

• By specifying fixed values.

• By stipulating a value table.

44. Structures can contain data only during the run time of a program (T/F)

- True.

45. What are the aggregate objects in the Dictionary?

- Views

- Match Code

- Lock object

46.What are base tables of an aggregate object?

The tables making up an aggregate object (primary and secondary) are called aggregate object.

47.The data of a view is not physically stored, but derived from one or more tables. (T/F).

-True.

48. What are the 2 other types of Views, which are not allowed in Release 3.0?

- Structure Views

- Entity Views.

49. What is a Match Code?

Match Code is a tool to help us to search for data records in the system. Match codes are an efficient and user-friendly search aid where key of a record is unknown.

50. What are the two levels in defining a Match Code?

- Match Code object

- Match Code Id.

51. What is the maximum number of match code Id's that can be defined for one Match code object ?

A match code Id is a one character ID that can be a letter or a number.

52. Can we define our own Match Code ID's for SAP Matchcodes ?

Yes, the numbers 0 to 9 are reserved for us to create our own Match Code IDs for a SAP defined Matchcode object.

53. What is an Update type with reference to a Match code ID?

If the data in one of the base tables of a matchcode ID changes, the matchcode data has to be updated. The update type stipulates when the matchcode is to be updated and how it is to be done. The update type also specifies which method is to be used for Building matchcodes . You must specify the update type when you define a matchcode ID.

54. Can matchcode object contain IDs with different update types ?

- Yes.

55. What are the update types possible ?

The following update types are possible:

Update type A: The matchcode data is updated asynchronously to database changes.

Update type S: The matchcode data is updated synchronously to database changes.

Update type P: The matchcode data is updated by the application program.

Update type I: Access to the matchcode data is managed using a database view.

Update type K: Access to the matchcode is achieved by calling a function module.

56. What are the two different ways of building a match code object ?

A match code can be built in two different ways :

• Logical structure : The matchcode data is set up temporarily at the moment when the match code is accessed. (Update type I, K)

• Physical structure : The match code data is physically stored in a seperate table in the database. (Update type A, S, P)

57. What are the differences between a Database index and a match code ?

• Match Code can contain fields from severeal tables whereas an index can contain fields from only one table.

• Match code objects can be built on transparent tables and pooled and cluster tables.

58. What is the function of a Domain?

• A domian describes the technical settings of a table field.

• A domain defines a value range, which sets the permissible data values for the fields, which refers to this domain.

• A single domain can be used as basis for any number of fields that are identical in structure.

59. Can you delete a domain which is being used by data elements ?

- No.

60. What are conversion routines ?

Non standard conversions from display format to sap internal format and vice-versa are implemented with so called conversion routines.

61. What is the function of a data element ?

A data element describes the role played by a domain in a technical context. A data element contains semantic information.

62. Can a domain, assigned to a data element be changed ?

Yes. We can do so by just overwriting the entry in the field domain).

63. Can you delete data element which is being used by table fields .

No.

64. Can you define a field without a data element ?

Yes. If you want to specify no data element and therefore no domain for a field, you can enter data type and field length and a ashort text directly in the table maintenance.

65. What are null values ?

If the value of a field in a table is undefined or unknown, it is called a null value.

66. What is the difference between a structure and a table ?

Structures are constructed the almost the same way as tables, the only difference using that no database table is generated from them.

67. What is a View ?

A view is a logical view on one or more tables. A view on one or more tables i.e, the data from a view is not actually physically stored instead being derived from one or more tables.

68. How many types of Views are there ?

- Database View

- Help View

- Projection View

- Maintenance View

69. What is Locking ?

When two users simultaneously attempt to access the same data record, this is synchronised by a lock mechanism.

70. What is database utility ?

Database utility is the interface betweenn the ABAP/4 Dictionary and the underlying the SAP system.

71. What are the basic fucntions of Database utility ?

The basic functions of database utility are :

- Create database objects

- Delete database objects

- Adjust database objects to changed ABAP/4 dictionary definition.

72. What is Repository Info. Systems ?

It is a tool with which you can make data stored in the ABAP/4 Dictionary available.

http://www.sapbrain.com/FAQs/TECHNICAL/SAP_ABAP_DATADICTIONARY_FAQ.html

CREATION OF TABLE

refer this link:

http://sap-img.com/abap/steps-to-creating-domains-data-elements-tables.htm

Regards

Madhu