You can also do this
DATA: l_test TYPE i.
SELECT-OPTIONS: sl_vbeln FOR g_vbeln.
DESCRIBE TABLE sl_vbeln[] LINES l_test.
IF l_test EQ 1.
"Logic here
ENDIF.
You can also do this
DATA: l_test TYPE i.
SELECT-OPTIONS: sl_vbeln FOR g_vbeln.
DESCRIBE TABLE sl_vbeln[] LINES l_test.
IF l_test EQ 1.
"Logic here
ENDIF.