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• line_exists ABAP_FUNCTION
ABAP_RELEXP - line_exists
ABAP_SYNTAX ... line_exists( table_exp ) ...
What does it do? The built-in predicate function line_exists checks whether a line of an internal table specified in the table expression table_exp exists and returns the corresponding truth value. In addition to single table expressions, chainings can also be specified for table_exp, whose result is a line of an internal table. Within line_exists, an explicitly specified table key in the table line table_line of the table expression is handled in the same way as a free search key specified for this table key.
Latest notes:
The table expression is only used to check the existence of the specified line. No temporary result is created.
The predicate function line_exists can be considered as a short form of the statement READ TABLE with the addition TRANSPORTING NO FIELDS followed by sy-subrc being checked.
The predicate function line_exists cannot be used to determine the line number in a table index of a search key used for the search, since table expressions do not fill the system field sy-tabix. The table function line_index can be used instead.
If a search key specified in table_line in the table expression covers the initial part of a secondary table key without being specified explicitly after KEY, a syntax check warning that can be hidden by a pragma occurs, since the function is generally more performant if the secondary key is specified explicitly.
As in other use cases of table expressions, line_exists must be used carefully to avoid duplicate selections. Therefore, line_exists should not be used to first check the existence of a line and then read it. Instead, the table expression can be assigned to a field symbol and then sy-subrc checked. If the line in question usually exists, the table expression can be specified in the required operand position and the exception CX_SY_ITAB_LINE_NOT_FOUND caught.
As well as assigning a table expression a default value for lines that are not found, there is also the option of checking the existence of lines. NON_V5_HINTS ABAP_HINT_END
