///查询生成交叉列表
CREATE TABLE AA
( AID int,
ANAME VARCHAR(10),
AKM VARCHAR(10)
)
insert into AA values(1,'A','G');
insert into AA values(2,'A','R');
insert into AA values(3,'A','B');
insert into AA values(4,'B','B');
insert into AA values(5,'B','R');
insert into AA values(6,'C','R');
select * from aa
select ANAME,
max(case AKM when 'R' then 'R' else '' end)
+max(case AKM when 'G' then 'G' else '' end)
+max(case AKM when 'B' then 'B' else '' end) AKM
from aa
group by ANAME
///MERGE语句是Oracle9i新增的语法,用来合并UPDATE和INSERT语句。通过MERGE语句,根据一张表或子查询的连接条件对另外一张表进行查询,连接条件匹配上的进行UPDATE,无法匹配的执行INSERT。这个语法仅需要一次全表扫描就完成了全部工作,执行效率要高于INSERT+UPDATE。
//表1
create table subs(msid number(9),
ms_type char(1),
areacode number(3)
);
//表2
create table acct(msid number(9),
bill_month number(6),
areacode number(3),
fee number(8,2) default 0.00);
//测试数据
insert into subs values(905310001,0,531);
insert into subs values(905320001,1,532);
insert into subs values(905330001,2,533);
commit;
一.下面先演示一下merge的基本功能
1) matched 和not matched clauses 同时使用
merge into acct a
using subs b on (a.msid=b.msid)
when MATCHED then
update set a.areacode=b.areacode
when NOT MATCHED then
insert(msid,bill_month,areacode)
values(b.msid,'200702',b.areacode);
2) 只有not matched clause,也就是只插入不更新
merge into acct a
using subs b on (a.msid=b.msid)
when NOT MATCHED then
insert(msid,bill_month,areacode)
values(b.msid,'200702',b.areacode);
3) 只有matched clause, 也就是只更新不插入
merge into acct a
using subs b on (a.msid=b.msid)
when MATCHED then
update set a.areacode=b.areacode
二.10g中增强一:条件操作
1) matched 和not matched clauses 同时使用
merge into acct a
using subs b on (a.msid=b.msid)
when MATCHED then
update set a.areacode=b.areacode
where b.ms_type=0
when NOT MATCHED then
insert(msid,bill_month,areacode)
values(b.msid,'200702',b.areacode)
where b.ms_type=0;
2) 只有not matched clause,也就是只插入不更新
merge into acct a
using subs b on (a.msid=b.msid)
when NOT MATCHED then
insert(msid,bill_month,areacode)
values(b.msid,'200702',b.areacode)
where b.ms_type=0;
3) 只有matched clause, 也就是只更新不插入
merge into acct a
using subs b on (a.msid=b.msid)
when MATCHED then
update set a.areacode=b.areacode
where b.ms_type=0;
三.10g中增强二:删除操作
merge into acct a
using subs b on (a.msid=b.msid)
when MATCHED then
update set a.areacode=b.areacode
delete where (b.ms_type!=0);
注意:
1.MERGE语句的UPDATE不能修改用于连接的列,否则会报错(on 后面的条件列就是联接)
2.using 后面可以是(SELECT msid ,areacode FROM subs GROUP by msid )
3.使用MERGE最常见的错误,造成这个错误的原因是由于通过连接条件得到的acct的记录不唯一
如果当点击LindButton时,触发事件可以这样写:
如下。。。
//html中。
<asp:LinkButton runat="server" ID="Option1" Text="Mocha Blast" CssClass="ContextMenuItem" OnClick="OnSelect"/><br />
//OnSelect方法
protected void OnSelect(object sender, EventArgs e)
{
lbl_select.Text = "You selected <b>" + ((LinkButton)sender).Text + "</b>.";
}

