-----测试表(oracle 10G):
create table portal_his.testuser(
XH numeric NOT NULL ,-----该字段值是唯一的;
deptid numeric NOT NULL ,
zwid numeric NULL ,
names varchar(20) NULL,
constraint testuser_pk PRIMARY KEY (XH)
);
------测试数据:
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');
求sql查询功能:
-----如果names字段值为''或null,则把该记录中deptid和zwid值相等的names字段值内容取一个出来(如果找到就取一个出来,没有找到就不管它).
xh deptid zwid names
1 1 2 a1
2 1 2 a1
3 1 3 a3
4 1 2 -----这里的查询
现在有两张表：文章主表A(articleId,articleTitle)，文章评论表B(commentId,articleId,commentTitle)
现在我想实现这样的功能：列出文章列表，其中每篇文章标题下面列出此文章的前2个文章评论，请问sql语句怎么写啊 ......
