SAP DATABASE SAP Info












ARTICLE ( Version: 0003)

Relational Databases

The relational data model
Application software models a part of the real world. This type of
modeling is based on the relational data model. A data model describes reality through formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.

A table is a two-dimensional matrix which consists of lines and columns (fields).

The value range of a field, i.e. the set of permitted values for the field, is also known as the domain of the field.

A field or combination of fields which uniquely identifies every line in a table is known as the key. This is a minimal attribute since, if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table entries.

Each table must have at least one key (primary key integrity), but many tables often often have several keys. During the modeling process, one key is defined as the primary key.

In the relational model, the relationship between objects is expressed in terms of foreign keys. A combination of fields in a table is known as a foreign key if it is also the primary key in another table.

In the R/3 System, the data model is managed in the ABAP/4 Dictionary.

<(>SQL<)>
The data required by all the applications is collected together and
managed in a pool known as the relational database. All the applications programs then address this database, normally by means of the extensively standardized <(>SQL<)> (Structured Query Language). The R/3 System supports a number of database systems. The embedding of <(>SQL<)> in the ABAP/4 language is achieved either with standardized Open SQL statements or with Native SQL in the language of the database system being used.

ARTICLE ( Version: 0004)

Relational Databases

The relational data model
Application software models a part of the real world. This type of
modeling is based on the relational data model. A data model describes reality through formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.

A table is a two-dimensional matrix which consists of lines and columns (fields).

The value range of a field, i.e. the set of permitted values for the field, is also known as the domain of the field.

A field or combination of fields which uniquely identifies every line in a table is known as the key. This is a minimal attribute since, if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table entries.

Each table must have at least one key (primary key integrity), but many tables often often have several keys. During the modeling process, one key is defined as the primary key.

In the relational model, the relationship between objects is expressed in terms of foreign keys. A combination of fields in a table is known as a foreign key if it is also the primary key in another table.

In the R/3 System, the data model is managed in the ABAP/4 Dictionary.

<(>SQL<)>
The data required by all the applications is collected together and
managed in a pool known as the relational database. All the applications programs then address this database, normally by means of the extensively standardized <(>SQL<)> (Structured Query Language). The R/3 System supports a number of database systems. The embedding of <(>SQL<)> in the ABAP/4 language is achieved either with standardized Open SQL statements or with Native SQL in the language of the database system being used.

Siehe auch Database Accesses
in the R/3 System

ARTICLE ( Version: 0028)

Relational Databases

The relational data model
Application software models a part of the real world. This type of
modeling is based on the relational data model. A data model describes reality through formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.
A table is a two-dimensional matrix which consists of lines and columns
(fields).
The value range of a field, i.e. the set of permitted values for the
field, is also known as the domain of the field.
A field or combination of fields which uniquely identifies every line in
a table is known as the key. This is a minimal attribute since, if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table entries.
Each table must have at least one key table
key (primary key integrity), but many tables often have several keys. During the modeling process, one key is defined as the primary key.
In the relational model, the relationship between objects is expressed
in terms of foreign key. A combination of fields in a table is known as a foreign key if it is also the primary key in another table.
In an ABAP-based SAP system, the data model is managed in the

ABAP Dictionary, which results in a
close compliance with the ABAP type concept.

The relational database
All the data relevant for all applications of an ABAP-based SAP
NetWeaver Application Server is collected and managed centrally in a relational database. All ABAP application programs work with this data. The largely standardized language <(>SQL<)> can be used to access relational databases. SAP NetWeaver Application Server ABAP supports database systems from different vendors. <(>SQL<)> is embedded in the ABAP language either with standardized Open SQL or vendor-specific Native SQL .



ARTICLE ( Version: 0032)

Relational Databases

The relational data model
Application software models a part of the real world. This type of
modeling is based on the relational data model. A data model describes reality through formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.
A table is a two-dimensional matrix which consists of lines and columns
(fields).
The value range of a field, i.e. the set of permitted values for the
field, is also known as the domain of the field.
A field or combination of fields which uniquely identifies every line in
a table is known as the key. This is a minimal attribute since, if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table entries.
Each table must have at least one key table
key (primary key integrity), but many tables often have several keys. During the modeling process, one key is defined as the primary key.
In the relational model, the relationship between objects is expressed
in terms of foreign key. A combination of fields in a table is known as a foreign key if it is also the primary key in another table.
In an AS ABAP, the data model is managed in the

ABAP Dictionary, which results in a
close compliance with the ABAP type concept .

The relational database
All the data relevant for all applications of an AS ABAP is
collected and managed centrally in a relational database. All ABAP application programs work with this data. The largely standardized language SQL can be used to access relational databases. Application Server ABAP supports database systems from different vendors. SQL is embedded in the ABAP language either with standardized Open SQL or vendor-specific Native SQL.



ARTICLE ( Version: 0039)

Relational Databases

The relational data model
Application software models a particular aspect of the real world. This
type of modeling is based on the relational data model. A data model describes reality through formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.
A table is a two-dimensional matrix consisting of lines and columns
(fields).
The value range of a field, i.e. the set of permitted values for the
field, is also known as the domain of the field.
A field or combination of fields that uniquely identifies every line in
a table is known as the key. This is a minimal attribute since, if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table entries.
Each table must have at least one table key
(primary key integrity), but many tables often have several keys. During the modeling process, one key is defined as the primary key.
In the relational model, the relationship between objects is expressed
in terms of foreign keys. A combination of fields in a table is known as a foreign key if it is also the primary key in another table.
In an AS ABAP, the data model is managed in the
ABAP Dictionary, which results in a close compliance with the ABAP type concept .

The relational database
All the data relevant for all applications of an AS ABAP is
collected and managed centrally in a relational database. All ABAP application programs work with this data by default. The largely standardized language SQL can be used to access relational databases. Application Server ABAP supports database systems from different vendors. SQL is embedded in the ABAP language either with standardized Open SQL or vendor-specific Native SQL .

Note
The primary table key, that is, the key fields of an AS ABAP
database table that form the table key, is limited to 900 bytes. If a key uses more than 120 bytes, the following restrictions apply:
  It is not possible to transport table contents by fully specifying the key values, but only by specifying the generic key value with a maximum length of 120 bytes.
  The table cannot be used as a base table for a lock object.

ARTICLE ( Version: 0041)

Relational Databases

The Relational Data Model
Application software models a part of the real world. This type of
modeling is based on the relational data model. A data model describes reality using formal structures. In the relational data model, the only formal structure used is known as a relation or table. All the information about the modeled area of reality is represented as values in tables.
A table is a two-dimensional matrix which consists of rows and columns
(fields).
The value range of a field (the set of permitted values for the field)
is also known as the domain of the field.
A field or combination of fields which uniquely identifies every row in
a table is known as the key. This is a minimal attribute: if one of the fields is removed from the key, the remaining fields cannot uniquely identify the table rows.
Each table must have at least one table key
(primary key integrity). However a table usually has multiple keys. During the modeling process, only one key is defined as the primary key.
In the relational model, the relationship between objects is expressed
in terms of a foreign key. A combination of fields in a table is known as a foreign key, if it is also the primary key in another table.
In an AS ABAP, the data model is managed in the
ABAP Dictionary, which results in a close compliance with the ABAP type concept .

The Relational Database
All the data relevant for all applications of an AS ABAP is
collected and managed centrally in a relational database. All ABAP application programs work with this data by default. The largely standardized language SQL can be used to access relational databases. Application Server ABAP supports database systems from different vendors. SQL is embedded in the ABAP language either with standardized Open SQL or vendor-specific Native SQL.

Note
The primary table key (key fields for a database table of AS ABAP
that build the table key) can have a total size of 900 bytes. However if a key is larger than 120 bytes, the restrictions apply:
  Table contents cannot be transported by specifying the complete key values. Instead you need to specify the generic key values with a maximum length of 120 bytes.
  The table cannot be used as the base table of a lock object.
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