ABAP CDS in ABAP Dictionary → ABAP CDS - Data Definitions → ABAP CDS - DDL for Data Definitions → ABAP CDS - DEFINE VIEW → ABAP CDS - SELECT → ABAP CDS - SELECT, Operands and Expressions →  Casting in a SELECT statement of a CDS view . The cast expression converts the value of the operand operand to the dictionary type specified by dtype . The result has the type dtype . The following can be specified for dtype :

Any data element . In this case, the optional addition PRESERVING TYPE can be specified. If this addition is specified, the built-in data type, the length of the operand and the number of decimal places, and the target data type must match exactly.

A built-in data type in ABAP Dictionary The addition PRESERVING TYPE cannot be specified in this case.

The following table shows the syntax for specifying built-in data types: dtype Dictionary Type abap.char( len ) CHAR with length len abap.clnt [ (3) ] abap.cuky( len ) CHAR with length len abap.curr(len,decimals) CURR with length len and decimals decimal places abap.dats [ (8) ] abap.dec(len,decimals) DEC with length len and decimals decimal places abap.fltp [ (16,16) ] abap.int1 [ (3) ] abap.int2 [ (5) ] abap.int4 [ (10) ] abap.int8 [ (19) ] abap.lang [ (1) ] abap.numc( len ) NUMC with length len abap.quan(len,decimals) QUAN with length len with decimals decimal places abap.raw(len) abap.sstring(len) SSTRING abap.tims [ (6) ] abap.unit( len ) CHAR with length len The actual length of the result is defined when the CDS view is activated and is must be at least as long as an explicitly defined length len . The predefined values can be specified for types with fixed lengths and decimal places, but this is not mandatory. The following can be specified for operand :

A literal without a domain prefix

A parameter

A session variable

A field of a data source data_source of the current CDS view

An aggregate expression

A path expression that identifies a field of a data source data_source

A built-in function

An arithmetic expression

A case distinction with CASE

A nested cast expression

Cast expressions can be specified in the SELECT list and in operand positions of expressions. The following table shows which combinations of built-in data types in ABAP Dictionary can currently be cast to each other and what the prerequisites are in each case. There is a special list of conversion rules for every combination. from/to SSTRING SSTRING If a built-in data type from ABAP Dictionary is specified for dtype , no further restrictions apply to combinations with "x". The following rules apply to the other combinations:

In combinations using "y", the target data type must be long enough.

In combinations using "z", the lengths of the data types must match exactly.

In the case of combinations with "p" or "d", no built-in data type from ABAP Dictionary can be specified. A data element must be specified as the target data type instead.

In combinations with "d", the data element can have a suitable target type in accordance with the table above and with any length.

In combinations with "p", the data element must have the built-in data type and the same length as the data type of the operand.

In the case of incompatible types, the content of the operand is converted to the target type (exceptions can be raised if values are not suitable). In compatible types, a syntax check warning occurs (unless the target data type is specified as a data element using the addition PRESERVING TYPE ). Notes

If a data element is specified for dtype , the result of the expression is given its semantic attributes. An exception to this is the use of the CAST expression within a case distinction using CASE ,

The addition PRESERVING TYPE can be used to perform a cast to data elements. This is done solely to modify the semantic attributes of the operand.

The characters in the surrogate area of the system code page UTF-16 are handled as two characters in cast expressions for strings. Care should be taken to avoid splitting these characters in cutoff operations.

When performing a conversion between currency fields with type CURR, it should be noted that CAST respects the decimal places defined for the type. In ABAP applications, on the other hand, the position of the decimal point is usually ignored.

An aggregate expression AVG has the type FLTP by default. The expression can be specified as an operand but it is not possible to cast to other types. Therefore there is a separate addition for AVG AS dtype .

For special conversions, which cannot be covered by a CAST expression, there are special predefined conversion functions :

FLTP_TO_DEC for converting FLTP to packed numbers.

Conversion functions for units and currencies

Example Cast expressions in a SELECT list. @AbapCatalog.sqlViewName: 'SALES_ORDER_VW'
define view sales_order as
select from snwd_so
association [1..*] to snwd_so_i as _item
on snwd_so.node_key = _item.parent_key
{ key snwd_so.node_key,
gross_amount as original_amount,
cast(gross_amount as abap.fltp) +
(cast( -gross_amount as abap.fltp) * 0.03)
as reduced_amount,
cast(gross_amount as abap.fltp) * 0.03
as overall_savings,
_item.so_item_pos as item_position,
_item.gross_amount as item_gross_amount,
cast(_item.gross_amount as abap.fltp) * 0.97
as item_savings } Example In the following view, the column char1 of the database DEMO_EXPRESSIONS is cast to the data element demo_char_text with the same technical attributes. In this case, it is advisable to specify the addition PRESERVING TYPE . @AbapCatalog.sqlViewName: 'DEMO_CDS_CAST_DE'
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view demo_cds_cast_data_element
as select from
demo_expressions
{
cast ( char1 as demo_char_text preserving type) as char_with_text
};

The following function module call returns the attributes of the view field The text shows that the semantic attributes of the data element were applied. The column char1 does not have its own text. DATA dfies_tab TYPE TABLE OF dfies.
CALL FUNCTION 'DDIF_FIELDINFO_GET'
EXPORTING
tabname   = 'DEMO_CDS_CAST_DE'
fieldname = 'CHAR_WITH_TEXT'
langu     = sy-langu
TABLES
dfies_tab = dfies_tab.
cl_demo_output=>display( dfies_tab[ 1 ]-fieldtext ). Example In the following view, a literal is given the technical and semantic attributes of the data element S_MANDT . @AbapCatalog.sqlViewName: 'DEMO_CDS_CSTCLNT'
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view demo_cds_cast_clnt
as select from
scarr
{
key cast ( 'XXX' as s_mandt )
as pseudo_client,
key carrid,
carrname
};

Continue
ABAP CDS - cast_expr, Conversion Rules