???? 最近在试着重新看下pl/sql,印象中pl/sql的if语句后面是可以跟elseif的。写了个简单的判断数字大小的语句：
?????
declare v_id number;begin v_id := &id; if v_id < 10 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value less than 10 '); elseif v_id < 20 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than20 '); elseif v_id < 30 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 30 '); end if;end;??? 在pl/sql下面elseif不变色，试着运行，直接报错了，从报错信息上看，在elseif附近存在错误，第一感觉是pl/sql?下elseif不是关键字,而是把elseif拆成else if,这样就ok了
???
set serveroutput on;declare v_id number;begin v_id := &id; if v_id < 10 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 10 '); else if v_id < 20 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 20 '); else if v_id < 30 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 30 '); else dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is greater than 30 '); end if; end if; end if;end;??? 这样写要特别注意end if和if的对应关系，一不小心漏掉一个end if就错了，有没有简单点的写法呢?
??? 其实pl/sql是支持else if这样的语法的，不过不是elseif,而是elsif,else少了一个e，用elsif写就是下面这样:
???
set serveroutput on;declare v_id number;begin v_id := &id; if v_id < 10 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 10 '); elsif v_id < 20 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 20 '); elsif v_id < 30 then dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is less than 30 '); else dbms_output.put_line('the value is:' || v_id || ' it''s true that the value is greater than 30 '); end if;end;??? 我上面的是在cmd window下运行的，如果想直接在sql window下按F8运行，请去掉:
???
set serveroutput on;
??? 如下所示:
??? 
??? 使用elsif写感觉简洁多了,elsif的语法如下：
???
IF THEN --do something...ELSIF THEN --do something...ELSIF THEN --do something...ELSE --do something...END IF;
??? 全文完。
?