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SqlServer中的case

ljwiie — Thu, 11 Jan 2007 02:26:00 GMT

做个查询�Q�字�D?值除3�Q�如�?1�Q�就用字�D?�?20�Q�如�?2�Q�字�D? �?30�Q�将差值大�?的数据选出来�?

SELECT col1, col2,
CASE
   WHEN col1 / 3 = 1 THEN col2 - 20
   WHEN col1 / 3 = 2 THEN col2 - 30
END AS difference
FROM price
WHERE (
CASE
   WHEN col1 / 3 = 1 THEN col2 - 20
   WHEN col1 / 3 = 2 THEN col2 - 30
END > 0)

ljwiie 2007-01-11 10:26 发表评论

oracle里面的round和java里面的round有何区别

ljwiie — Thu, 26 Oct 2006 02:08:00 GMT

oracle里面round为四舍五入，�l�对值四舍五入后加符�?/p>

java里面�?br />Math.round(a): (long)Math.floor(a + 0.5d)
Math.floor(a): 不大于a的最大整�?/p>

ljwiie 2006-10-26 10:08 发表评论

ljwiie — Tue, 24 Oct 2006 02:36:00 GMT

--商品��h��信息�?br />create table GOODS(
ID NUMBER,
NAME VARCHAR2(10),
PRICE NUMBER(10,2),
AREA VARCHAR2(10)
);
--��d��主键
alter table GOODS
add constraint PK_GOODS primary key (ID);
--��d��注视
comment on table GOODS is '商品信息�?;
comment on column GOODS.ID is '商品�~�号';
comment on column GOODS.NAME is '商品名称';
comment on column GOODS.PRICE is '商品��h��';
comment on column GOODS.AREA is '销售地�?;

--��d��数据
insert into GOODS values(11,'�Ҏ��','2.5','成都1');
insert into GOODS values(12,'�Ҏ��','3.5','成都2');
insert into GOODS values(13,'�Ҏ��','1.5','成都3');
insert into GOODS values(14,'�Ҏ��','2.0','成都4');

insert into GOODS values(21,'香蕉','1.7','成都1');
insert into GOODS values(22,'香蕉','1.5','成都2');
insert into GOODS values(23,'香蕉','1.6','成都3');
insert into GOODS values(24,'香蕉','2.0','成都4');

--查询某种商品�q�_��?br />select NAME,avg(PRICE) from GOODS group by NAME;

--��商品�h格更��Cؓ同种商品�Q�名�U�相同）的��^均�h�?br />update GOODS A
set A.PRICE =
(
select avg(PRICE) from GOODS where NAME = A.NAME
);

--执行环境oracle

ljwiie 2006-10-24 10:36 发表评论

oracle注释

ljwiie — Thu, 14 Sep 2006 08:39:00 GMT

��d��表注�?br />comment on table 表名 is '表注�?
��d��字段注释
comment on column 表名.字段�?is '字段名注�?

查询表注�?br />select * from user_tab_comments
查询字段注释
select * from user_col_comments

查询以TAB_开头的表的注释
where table_name like 'TAB/_%' escape '/'
�׃��下划�U�在数据库中代表��L��单个字符,所以需要�{�?br />单引��L��单引号字�W��{�?/p>

ljwiie 2006-09-14 16:39 发表评论

oracle常用函数

ljwiie — Fri, 18 Aug 2006 05:53:00 GMT

|| 字符�q�接
initcap 首字母大�?
lower 转换为小写字�W?br />upper 转换为大�?br />lpad 左填�?br />rpad 叛_��?br />ltrim 去除左边的空�?br />rtrim 去除双��的空�?br />alltrim 去除两边的空�?br />replace 替换
translate 转换
ascii 求ASC�?br />chr asc码变字符
substr 字符截取函数
instr ��试字符串出现的位置
length 字符串的长度

sysdate �pȝ��旉��
add_months ��d��月䆾,得到一个新的日�?br />trunc 截取�q�月�?br />last_day 某月的最后一�?br />months_between 两个日期之间的月�?/p>

to_char 把日期或数字�c�d��变�ؓ字符�?br />to_number 把字�W�串变成数字
to_date 把字�W�串变成日期

ceil 不小于x的最��整�?br />floor 不大于x的最大整�?br />round 四舍五入
trunc 舍去��数
mod(x,n) x除以n以后的余�?br />power(x,y) x的y�ơ方

greatest 求最大�?br />least 求最��?br />nvl �I��D�{换函�?/p>

decode (if...elseif...elseif...else�l�构)

sign(x) 判断正负
x是正 1
x是负 -1
x�?   0

rownum 行号�Q�必��M��?lt;=的关�p�L��较运��符

ljwiie 2006-08-18 13:53 发表评论