ABAP Keyword Documentation → ABAP - Reference → Processing External Data → ABAP - Database Accesses → Open SQL → Open SQL - Overview
Open SQL - General
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Scope of Open SQL
Open SQL defines the subset of ABAP statements that enable direct access to data from the central database of the current AS ABAP. The Open SQL statements form the DML part of SQL in ABAP, which is supported by all database systems.
We differentiate between:
The statements of Open SQL are converted to database-specific SQL in the Open SQL interface of the database interface. They are then transferred to the database system and executed there. Open SQL statements can be used exclusively to access database tables that are declared in the ABAP Dictionary. It is also possible to access these using views.
By default, the central database of the AS ABAP is accessed. It is also possible to access other databases using secondary database connections.
Each Open SQL statement is synonymous with an access to the database. This applies in particular with
SELECT statements that end in
to be read and to be modified is transported in packages between the database server and the current application server. You can configure the size of the packages using
(for example, the default value for Oracle is 65 KB). The number of characters that can be transported in one package depends on whether the system is a Unicode system or a non-Unicode system.
To improve performance when accessing the database, you can activate SAP buffering to avoid accessing the database directly each time.
If more than approximately 2^32 entries are addressed in a single database access, the behavior of the database is undefined.
Open SQL works with automatic
client handling that always accesses the current client. The current client is the content of the system field
When client-specific database tables are accessed, the
cannot be explicitly specified in
conditions, or it is ignored by entries in work areas of modifying statements. You can switch off automatic client handling using the addition
- The client data from an AS ABAP is depicted in closed units. No cross-client access to databases
should take place in application programs. For this reason, the addition
CLIENT SPECIFIEDshould never be used and no access to
sy-mandtshould take place.
- True multitenancy, with which the system ensures that different tenants' application data is isolated from each other, is not supported by the ABAP runtime environment in the current release.
When using the modifying statements (
DELETE), it is important to keep data storage consistent. The
LUW concept is designed for this purpose. In application programs of an AS ABAP, the implicit
database LUWs are normally not sufficient for consistent data storage. Instead, you need to program explicit
SAP LUWs, which normally contain several database LUWs (refer to the section on
More information: Performance Advice for Open SQL.