14.3.Intersection of internal tables
数据源表 ITAB1 和ITAB2都是STANDARD TABLES，假定ITAB1比ITAB2包含更多的记录。 否则，需要使用 "DESCRIBE TABLE ... LINES ..."语句计算内表包含的记录数。假定2个内表中的记录都遵从主键K唯一。
算法在计算中需要使用一个有唯一主键K的临时 内表,该内表是ITAB1数据的复制，匹配的数据被复制到ITAB3,以下两个示例的区别在于临时内表分别为SORTED TABLE和HASHED TABLE，对于LOOP中的READ语句，HASHED TABLE比SORTED TABLE更快。
STAB1 = ITAB1.
REFRESH ITAB3.
LOOP AT ITAB2 ASSIGNING <WA>.
READ TABLE STAB1 FROM <WA>
TRANSPORTING NO FIELDS.
IF SY-SUBRC = 0.
APPEND <WA> TO ITAB3.
ENDIF.
ENDLOOP.
FREE STAB1.
<Using a sorted table temporarily >
HTAB1 = ITAB1.
REFRESH ITAB3.
LOOP AT ITAB2 ASSIGNING <WA>.
READ TABLE HTAB1 FROM <WA>
TRANSPORTING NO FIELDS.
IF SY-SUBRC = 0.
APPEND <WA> TO ITAB3.
ENDIF.
ENDLOOP.
FREE HTAB1.
<Using a hashed table temporarily>
REFRESH ITAB3.
LOOP AT ITAB2 ASSIGNING <WA>.
READ TABLE STAB1 FROM <WA>
TRANSPORTING NO FIELDS.
IF SY-SUBRC = 0.
APPEND <WA> TO ITAB3.
ENDIF.
ENDLOOP.
FREE STAB1.
<Using a sorted table temporarily >
HTAB1 = ITAB1.
REFRESH ITAB3.
LOOP AT ITAB2 ASSIGNING <WA>.
READ TABLE HTAB1 FROM <WA>
TRANSPORTING NO FIELDS.
IF SY-SUBRC = 0.
APPEND <WA> TO ITAB3.
ENDIF.
ENDLOOP.
FREE HTAB1.
<Using a hashed table temporarily>
