¸ßÊÖ,ÇóÒ»oracle sql²éѯ¹¦ÄÜ - Oracle / ¿ª·¢

-----²âÊÔ±í(oracle 10G):
create table portal_his.testuser(
XH numeric NOT NULL ,-----¸Ã×Ö¶ÎÖµÊÇΨһµÄ;
deptid numeric NOT NULL ,
zwid numeric NULL ,
names varchar(20) NULL,
constraint testuser_pk PRIMARY KEY (XH) 
);


------²âÊÔÊý¾Ý:
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(1,1,2,'a1');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(2,1,2,'a1');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(3,1,3,'a3');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(4,1,2,'');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(5,2,4,'a4');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(6,2,6,'a4');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(7,2,10,'a5');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(8,3,10,'');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(9,2,10,'');
insert into portal_his.testuser(XH,deptid,zwid,names) 
values(10,3,10,'a7');


Çósql²éѯ¹¦ÄÜ:
-----Èç¹ûnames×Ö¶ÎֵΪ''»ònull,Ôò°Ñ¸Ã¼Ç¼ÖÐdeptidºÍzwidÖµÏàµÈµÄnames×Ö¶ÎÖµÄÚÈÝÈ¡Ò»¸ö³öÀ´(Èç¹ûÕÒµ½¾ÍÈ¡Ò»¸ö³öÀ´,ûÓÐÕÒµ½¾Í²»¹ÜËü).
xh deptid zwid names
1 1 2 a1
2 1 2 a1
3 1 3 a3
4 1 2 -----ÕâÀïµÄ²éѯ