Trouble Shooting of Oracle

JavaCoffe — Thu, 08 Apr 2010 06:08:00 GMT

In summary, you should avoid soft and hard parses as
much as possible because they inhibit the scalability of applications.

The result of a parse operation is a parent cursor and a child cursor stored in the library cache.

The key information related to a parent cursor is the text of a SQL statement.

Therefore,
several SQL statements share the same parent cursor if their text is exactly the same

JavaCoffe 2010-04-08 14:08 发表评论

group by 当中使用 Rollup和Cube,Grouping,Grouping Set

JavaCoffe — Tue, 23 Jun 2009 09:27:00 GMT

select deptno,job,avg(sal),max(sal) from emp group by rollup( deptno,job);
统计第一个维度的的总和。

select deptno,job,avg(sal),max(sal) from emp group by cube( deptno,job);
在统计第一个维度的基础上，在统计第二个维度竖列的综合。

select deptno,job,avg(sal),max(sal) ,grouping(deptno),grouping(job) from emp group by cube( deptno,job);
确定统计结果是否用到了特定的列。

select deptno,job,avg(sal),max(sal) from emp group by GROUPING SETS( deptno,job);
显示多种分组统计的结果。

JavaCoffe 2009-06-23 17:27 发表评论

insert 多行插入

JavaCoffe — Tue, 23 Jun 2009 03:37:00 GMT

1、单行插入
    insert into [(column,[column,...])]values(value,[value,....])
    使用default 插入数据，在values当中使用default会插入默认值，或者NULL

2、使用字查询插入数据。
      INSERT INTO subquery.

     INSERT ALL insert_into_clause [value clause]subquery
    INSERT conditional_insert_clause subquery

    insert all
    when deptno = 10 then into dept10
    when deptno = 20 then into dept20
    else into others
     select * from emp;

      INSERT FIRST(如果先前的数据已经被使用过，那么在后续当中则不会再使用这些数据)
    when deptno = 10 then into dept10
    when deptno = 20 then into dept20
    else into others
     select * from emp;

另外提供create table as subquery;

JavaCoffe 2009-06-23 11:37 发表评论