SAP TABLE EXPRESSIONS documentation, setup help and example usage

table_exp - Table Expressions

Syntax
... itab[ itab_line ] ...

Effect
A table expression consists of an internal table itab , followed directly by a row ( itab_line ) specified in square brackets [ ] . The expression finds the specified row in the internal table and returns it as a result that can be used as follows:

Reader Positions

A table expression can be specified in general expression positions and functional operand positions with an appropriate operand type . The result is used here as an operand. The category of the result can be controlled in operand positions using constructor operators .

A table expression can be specified as a special expression variant for the memory area in the statement ASSIGN .

A table expression can be specified as an argument of the table function line_index and the predicate function line_exists .

Writer Positions

A table expression can be specified as a writable expression in result positions . Once found, the row in question can be modified directly here.

The internal table itab must be specified directly using its name, a field symbol, or a dereferenced data reference as described under Reader Positions . In a table with header line , the table body is addressed and not the header line.
The structure component selector -
can be used to access components of the row in question and direct chainings [ ... ][ ... ] of multiple table expressions. Table expression cannot yet, however, be specified on the left side of
object component selector - .
If the specified row is not found, a handleable expression of the class CX_SY_ITAB_LINE_NOT_FOUND is raised in all operand positions, except when

a table expression is used in the statement ASSIGN , where

sy-subrc is set to the value 4,

when used in the predicate function

line_exists , where the logical value "false" is returned,

when used in the table function

line_index , where the value 0 is returned.

Notes

Unlike other syntax representations in the ABAP key word documentation, the " [ " and " ] " characters are part of the syntax.

In table expressions, the empty square brackets [] cannot be specified behind itab . In other operand positions, these empty brackets distinguish the table body from

header lines .

Functions and constructor expressions cannot currently be specified for itab , but the table expressions shown under Chainings are possible.

A table expression cannot be followed directly by a specified offset/length +off(len) , but this is possible after a

chaining whose final place is a suitable structure component after a structure component selector.

Duplicate selections (multiple reads performed on the same row of an internal table in different expressions) must be avoided manually. In these cases, a selection should be made before the statement and the result referenced by a field symbol or reference variable.

Each table expression can be view as a short form for a variant of the statement READ TABLE that enables reads to be performed on rows of internal tables in operand positions.

Unlike READ TABLE , a table expression does not modify the value of the system field sy-tabix .

Like the statement READ TABLE , a table expression is a single row read. If multiple rows of an internal table are to be read, the statement LOOP generally displays better performance than using table expressions in a loop.

Example
The content of the component carrid of the row of the internal table carrier_tab is passed to the method get_spfli . In this table, the component carrname of the secondary key name has a specific value.
DATA carrier_tab TYPE HASHED TABLE OF scarr
WITH UNIQUE KEY carrid
WITH NON-UNIQUE SORTED KEY name COMPONENTS carrname.

SELECT * FROM scarr INTO TABLE carrier_tab.

TRY.
DATA(flight_tab) = cl_demo_spfli=>get_spfli(
carrier_tab[ KEY name
COMPONENTS carrname = 'United Airlines' ]-carrid ).
cl_demo_output=>display( flight_tab ).
CATCH cx_sy_itab_line_not_found.
cl_demo_output=>display( `Nothing found` ).
ENDTRY.

Example
Here, the first calculation with table rows is a bad example of how to use table expressions. The same selection is made three times in the same statement. The second calculation shows how this can be avoided by using an assignment to a field symbol .
DATA itab TYPE TABLE OF i.
itab = VALUE #( ( 3 ) ( 5 ) ).

"Bad example
itab[ table_line = 3 ] =
itab[ table_line = 3 ] * itab[ table_line = 3 ].

"Good example
ASSIGN itab[ table_line = 5 ] TO FIELD-SYMBOL(<(><<)>fs>).
<(><<)>fs> = <(><<)>fs> * <(><<)>fs>.

Examples
The program DEMO_TABLE_EXPRESSIONS
shows further examples of how to use table expressions.



Runtime Exceptions

Catchable Exceptions
CX_SY_ITAB_LINE_NOT_FOUND

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