if
if<condition_1>.
<statements...>
endif.
if...else
if<condition_1>.
<statement block 1>.
else.
<statement block 2>.
endif.
嵌套if
if<condition_1>.
<statement block>.
if<condition_2>.
<statement block>.
else.
<statement block>.
endif.
else <statement block>.
endif.
case
case <field>.
when <abc>.
<statement block>.
when <def>.
<statement block>.
when <pqr>,
<statement block>.
...
...
when <xyz>.
<statement block>.
when others.
<statement block>.
endcase.
