oracle db2命令对比（整理中）

1).如何取一表前n笔记录的Oracle和DB2的写法
  Oracle： select * from table_a where rownum<=100;
  DB2：    select * from table_a fetch first 100 rows only;

2).如何取得当前日期的Oracle和DB2的写法
  Oracle：select sysdate from dual;
  DB2：select current timestamp from sysibm.sysdummy1;

3).如何连接字段的Oracle和DB2的写法
Oracle : select emp_no||emp_nam from bsempms; Select concat(emp_no,emp_nam) from bsempms;

DB2: Select emp_no||emp_nam from db2admin.bsempms; select emp_no concat emp_nam from db2admin.bsempms;

4).如何查询表的结构的Oracle和DB2的写法
  Oracle： select sysdate from dual;
  DB2： select current timestamp from sysibm.sysdummy1;

5).内连接INNER JOIN的Oracle和DB2的写法
  Oracle： select a.* from bsempms a,bsdptms b where a.dpt_no=b.dpt_no;
  DB2：select * from db2admin.bsempms inner join db2admin.bsdptms on db2admin.bsempms.dpt_no=db2admin.bsdptms.dpt_no;

6).外连接的Oracle和DB2的写法(右外连接,左外连接,完全外连接,组合外连接)
  Oracle: select a.* from bsempms a,bsdptms b where a.dpt_no=b.dpt_no(+);
              select a.* from bsempms a,bsdptms b where a.dpt_no(+)=b.dpt_no;

  DB2: 

select * from db2admin.bsempms right outer join db2admin.bsdptms on db2admin.bsempms.dpt_no=db2admin.bsdptms.dpt_no;

select * from db2admin.bsempms left outer join db2admin.bsdptms on db2admin.bsempms.dpt_no=db2admin.bsdptms.dpt_no;

select * from db2admin.bsempms full outer join db2admin.bsdptms on db2admin.bsempms.dpt_no=db2admin.bsdptms.dpt_no;

7）minus

select a,b from table_a
minus
select a, b from table_b

select a,b from table_a
except
select a, b from table_b

。。。

继续阅读：

http://blog.csdn.net/wwxtu24/article/details/5386254