½ñÌìµÄoracleÃæÊÔÌâ2 - Oracle / »ù´¡ºÍ¹ÜÀí

ÓÐÒ»ÕűíA,ÊôÐÔid,name,extend,ÆäÖÐextend×Ö¶ÎΪ¿Õ£¬Ò»ÕűíC,ÊôÐÔid ,extend,c.extend²»Îª¿Õ,
ÆäÖбíC.idÊDZíA.id×Ó¼¯¡£ÏÖÔÚÐèҪʹÓÃSQLʵÏÖÕâÑùµÄ¹¦ÄÜ
Èç¹ûA.id = C.id ÄÇô a.extend = c.extend ·ñÔò a.extend = 0 £¿

---

select a.id,a.name,a.extend
from a,c
where a.id=c.id and a.extend = c.extend
union all
select a.id,a.name,a.extend
from a,c
where a.extend = 0 and not exists(select 1
from c where a.id=c.id)

---

select A.id,nvl(A.extend,0) from A,C where A.id = C.id(+)

---

¶Ô£¬ÓÃnvlµÄ£¬Â¥Ö÷Ã÷°×µÄ

---

ÒýÓÃ

select a.id,a.name,a.extend
from a,c
where a.id=c.id and a.extend = c.extend
union all
select a.id,a.name,a.extend
from a,c
where a.extend = 0 and not exists(select 1
from c where a.id=c.id)

²»ºÃÒâ˼£¬ÎÒûÓÐ˵Ã÷°×£¬a.extend = c.extend ·ñÔò a.extend = 0 ÊǸ´ÖƵÄÒâ˼£¬¾ÍÊÇ°Ñc.extend¸³Öµ¸øa.extend.

---

ÒýÓÃ

ÓÐÒ»ÕűíA,ÊôÐÔid,name,extend,ÆäÖÐextend×Ö¶ÎΪ¿Õ£¬Ò»ÕűíC,ÊôÐÔid ,extend,c.extend²»Îª¿Õ,
ÆäÖбíC.idÊDZíA.id×Ó¼¯¡£ÏÖÔÚÐèҪʹÓÃSQLʵÏÖÕâÑùµÄ¹¦ÄÜ
Èç¹ûA.id = C.id ÄÇô a.extend = c.extend ·ñÔò a.extend = 0 £¿

SQL code:


select a.id,a.name,nvl2(a.extend,0)
from a,c
where a.id=c.id

---

ÒýÓÃ

select A.id,n