ABAP CDS - session_variable - ABAP Keyword Documentation

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ABAP CDS - session_variable

Syntax

... $session.vname ...

Effect

Specifies a session variable vname in an operand position in a SELECT statement of a CDS view. The variable is case-sensitive. $session.vname, $Session.Vname, and $SESSION.VNAME can all be used. No other spellings are allowed.

Session variables have a predefined name and are set to a predefined value when the CDS view is used in Open SQL. This also applies to CDS views that are used as data sources in other CDS views. The following session variables exist:

vname	Value in Open SQL Accesses
user	Current user name, nominal value of the ABAP system field sy-uname
client	Current client. The default value is the nominal value of the ABAP system field sy-mandt. In reads with an Open SQL statement (with the statement USING CLIENT) and in calls of an AMDP method from ABAP (in whose declaration the addition AMDP OPTIONS CDS SESSION CLIENT is specified), the value specified here.
system_language	Text environment language of the current internal session, nominal value of the ABAP system field sy-langu
system_date	Current system date of the AS ABAP, nominal value of the ABAP system field sy-datum

Notes

From a technical perspective, session variables indicate global variables of the current database that are set to their value when the CDS view is used in Open SQL. If Open SQL is not used to access a CDS view with session variables, the content of the variables is undefined (with the exception of the SAP HANA database).

On a SAP HANA database used as a standard AS ABAP database, the ABAP-specific session variables are called APPLICATIONUSER, CDS_CLIENT, LOCALE_SAP, and SAP_SYSTEM_DATE and exist and are set independently of ABAP CDS and Open SQL. They can be accessed using the database function SESSION_CONTEXT.

A further ABAP-specific session variable CLIENT in the SAP HANA database always contains the current client of the ABAP session and is not modified by the Open SQL addition USING CLIENT or by ABAP calls of an AMDP method (in whose declaration the addition AMDP OPTIONS CDS SESSION CLIENT is specified). The HANA session variable CLIENT does not have a corresponding variable in ABAP CDS.

For input parameters of CDS views annotated with the special annotation environment.systemField, Open SQL can pass the values of the session variables specified here automatically too. It is generally preferable to use this type of local input parameter.

In existing CDS views without corresponding input parameters, session variables can be passed to the input parameters of CDS views or CDS table functions used there.

In access to a CDS view using the Open SQL statement SELECT where the session variable client is used, the addition CLIENT SPECIFIED cannot be used. The addition USING CLIENT can be used and is respected in the session variable for the duration of the Open SQL statement.

In the CDS database view of a CDS view whose client handling is set by the annotation @ClientHandling.algorithm: #SESSION_VARIABLE, the value of the session variable client is used in WHERE conditions for the client column.

A CDS view that accesses a session variable directly or using a view cannot usually be buffered. Only client-specific views that access the session variable client directly can be buffered.

Example

The following CDS view contains the possible session variables in the SELECT list. The program DEMO_CDS_SESSION_VARIABLES uses Open SQL to access the view and fills the session variables with the associated values. Here, it is possible to define whether USING CLIENT is used or not.

@AbapCatalog.sqlViewName: 'DEMO_CDS_SESSVAR'
@AccessControl.authorizationCheck: #NOT_ALLOWED
define view demo_cds_session_variables
  as select from
    demo_expressions
    {
      id,
      $session.user            as system_user,
      $session.client          as system_client,
      $session.system_language as system_language,
      $session.system_date     as system_date
    }

Example

The following CDS view DEMO_CDS_SELECT_T100 accesses a further CDS view DEMO_CDS_SELECT_T100_LANGU with a language input parameter to which the annotation environment.systemField with the value system_language is assigned. Unlike in Open SQL, there is no implicit pass of the actual parameter to the input parameter here and the corresponding session variable $session.system_language is passed instead. The program DEMO_CDS_T100 uses Open SQL to access both views and the result is identical. When DEMO_CDS_SELECT_T100_LANGU is accessed, the value of the system field sy-langu is passed implicitly to the input parameter. When DEMO_CDS_SELECT_T100 is accessed, the session variable $session.system_language is filled with this value.

@AbapCatalog.sqlViewName: 'DEMO_CDS_T100'
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view demo_cds_select_t100
as select from
demo_cds_select_t100_langu( p_langu: $session.system_language )
{
*
}

@AbapCatalog.sqlViewName: 'DEMO_CDS_T100_LG'
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view demo_cds_select_t100_langu
with parameters
@Environment.systemField:#SYSTEM_LANGUAGE
p_langu : lang
as select from
t100
{
*
}
where
sprsl = :p_langu
and arbgb = 'SABAPDEMOS'