freefly
一门技术,如果不能讲出来,那么就是没有理解,如果不能很好的讲出来,那么就是理解不够透彻!
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  1. create view

          ORACLE:    CREATE OR REPLACE VIEW V_FA_ADD_CO AS

             SQLSEVER:    IF EXISTS (SELECT 1
                                                            FROM  sysobjects
                                                            WHERE  idobject_id ('V_FA_ADD_CO')
                                                             AND   type = 'V')
                                    DROP VIEW V_FA_ADD_CO;
                                    CREATE VIEW V_FA_ADD_CO AS

    
2. the equal between join and (+)
      
       the table(its fields stay with (+)) right  join another  corresponding   table.
       for example: select * from a,b where a.id=b.id(+)
               equals  select * from b rigth join a on a.id=b.id
               equals  select * from a left join a on a.id=b.id

        notes:join先匹配有对应的记录,
              (+)却是按顺序来的
 

    3. substr,substring
     
for example: there is a table's field "userName" and it's value is "wanghuiling".
       sqlserver: substring(userName,0,4) = "wan",substring(userName,1,4) = "wang"
       oracle:  substr(userName,0,4)="wang",substr(userName,1,4)="wang"
   
 4. link sign
     sqlserver: "+"
    
oracle:"||"
 
5. update a table's some fields

     for example:there are two tables: students1 and students2

     sqlserver:update students     (can't use alias)
                   set name=s2.name,sex=s2.sex,age=s2.age,tel=s2.tel
                   from students s2 where s1.id=s2.id;
     oracle: update students1 s1
               set (name,sex,age,tel)=
               (select name,sex,age,tel from students2 s2 where s1.id=s2.id);

6. Date
    for example:there are a field of  date type:input_date  and its value is 2007-08-09.   
    sqlserver : year(input_date)=2007,month(input_date)=8,day(input_date)=9
     oracle : to_char(input_date,'YYYY')=2007, to_char(input_date,'MM')=8, to_char(input_date,'DD')=9

     sDate : a java String variable
     sqlserver : input_date = '"+sDate+"' 
     oracle : input_date =  to_char( '" + sDate + "',' 'YYYY-MM-DD'')

posted on 2006-12-31 15:42 freefly 阅读(490) 评论(0)  编辑  收藏 所属分类: Database

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