Try this code :--
TYPES: BEGIN OF gt_/BIC/B0001371000,
REQUEST TYPE /BIC/B0001371000-REQUEST,
DATUM TYPE RSREQDONE-DATUM
END OF gt_/BIC/B0001371000.
DATA: gs_/BIC/B0001371000 TYPE gt_/BIC/B0001371000,
gt_/BIC/B0001371000 TYPE SORTED TABLE OF gt_/BIC/B0001371000
WITH NON-UNIQUE KEY REQUEST.
TYPES: BEGIN OF gt_RSREQDONE,
RNR TYPE RSREQDONE-RNR,
datum TYPE RSREQDONE-DATUM,
END OF gt_RSREQDONE.
DATA: gs_RSREQDONE TYPE gt_RSREQDONE,
gt_RSREQDONE TYPE SORTED TABLE OF gt_RSREQDONE
WITH NON-UNIQUE KEY RNR.
IF SOURCE_PACKAGE[] IS NOT INITIAL.
SELECT DATUM
FROM /BIC/B0001371000
INNER JOIN RSREQDONE
ON /BIC/B0001371000 . REQUEST = RSREQDONE . REQUEST
INTO CORRESPONDING FIELDS OF TABLE
gt_/BIC/B0001371000
FOR ALL ENTRIES IN gt_/BIC/B0001371000
WHERE RNR EQ gt_/BIC/B0001371000-REQUEST.
endif.
At field level :
READ TABLE gt_/BIC/B0001371000 INTO gs_/BIC/B0001371000
WITH KEY RNR = gs_/BIC/B0001371000-REQUEST
BINARY SEARCH.
IF sy-subrc = 0.
RESULT = gs_/BIC/B0001371000-DATUM.
ENDIF.