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刚刚电面完，累死我了

刚刚电面完，累死我了# Database - 数据库

c*d2008-08-22 07:08

1 楼

刚刚面试完MS SQL Server，一共分了4个部分
第一个部分是db的基本问题
第二个部分是MS SQL admin的问题
第三个部分是关于操作系统和网络
第四个部分是数据库troubleshooting
前两个部分很简单，都是应该知道的概念
比如什么是transaction/store procedure/view/index/out join/having and where/
dead lock and how to minimize it/clustered and non-clustered index/how to
move the database from one server to another one/isolation levels/locks
levels
第三个部分对我来说比较难
以前一直做数据库管理，从来没怎么好好看过操作系统和网络
有些问题应该很简单，但是不知道正式的definition是什么
比如，process和thread有啥区别，啥是multi-tasking
multi-tasking的两种方式（说了两个名词，听都没听说过，直接pass）

m*22008-08-22 07:08

2 楼

恩,发包子好...支持...

【在 c*****d 的大作中提到】

: 刚刚面试完MS SQL Server，一共分了4个部分
: 第一个部分是db的基本问题
: 第二个部分是MS SQL admin的问题
: 第三个部分是关于操作系统和网络
: 第四个部分是数据库troubleshooting
: 前两个部分很简单，都是应该知道的概念
: 比如什么是transaction/store procedure/view/index/out join/having and where/
: dead lock and how to minimize it/clustered and non-clustered index/how to
: move the database from one server to another one/isolation levels/locks
: levels

B*g2008-08-22 07:08

3 楼

我猜multi task是multi threads和multi processes比较变态。
multi threads 就是一个cpu，几个threads大家轮着用。
multi processes就是多个cpu。

【在 c*****d 的大作中提到】

c*t2008-08-22 07:08

4 楼

I am not an OS guy, but from memory:
Multi-threads are usually within an application process, thus
shares memory accesses. It is considered light-weight.
Multi-processing usually means using separate application processes,
and communicate through messaging. It is more of a heavy-weight.
Both can use multiple CPUs.
In addition, threads can be user level or kernel supported on some
OS'es (e.g. Sun Solaris). I think that Linux process / thread are
pretty much the same.
Multi-tasking doesn't have

【在 B*****g 的大作中提到】

: 我猜multi task是multi threads和multi processes比较变态。
: multi threads 就是一个cpu，几个threads大家轮着用。
: multi processes就是多个cpu。

j*n2008-08-22 07:08

5 楼

嗯，我和beijing 你要发大包子，理解正确吧？
哈哈

B*g2008-08-22 07:08

6 楼

这个版18个包子应该发不出去，呵呵

【在 j*****n 的大作中提到】

: 嗯，我和beijing 你要发大包子，理解正确吧？
: 哈哈

c*e2008-08-22 07:08

7 楼

re

【在 c*****d 的大作中提到】

w*r2008-08-22 07:08

8 楼

Multi-Thread:; share the same process ID in OS, since it is the same process
id it can share data on the heap. Context switching is done within the same
process. Essential point: logically the logic address 0 for all the threads
pointing to the same location
Multi-process: different pID, each one of the PID has totally different
context. Context switching is controlled by OS like everything else. data
share is achieved by external mechanisms provided by os, such as named pipe,
socket, file, etce

【在 c*****t 的大作中提到】

: I am not an OS guy, but from memory:
: Multi-threads are usually within an application process, thus
: shares memory accesses. It is considered light-weight.
: Multi-processing usually means using separate application processes,
: and communicate through messaging. It is more of a heavy-weight.
: Both can use multiple CPUs.
: In addition, threads can be user level or kernel supported on some
: OS'es (e.g. Sun Solaris). I think that Linux process / thread are
: pretty much the same.
: Multi-tasking doesn't have

a*t2008-08-22 07:08

9 楼

cool

【在 c*****d 的大作中提到】

a*t2008-08-22 07:08

10 楼

容易解决, 给我10个

【在 B*****g 的大作中提到】

: 这个版18个包子应该发不出去，呵呵

c*d2008-08-22 07:08

11 楼

呵呵，想在这个版发18个包子还真不容易
现在发包子，截至到Assailant

x*y2008-08-22 07:08

12 楼

outer join: retrieve both matching and non-matching rows. That is, outer
join does not require each record in the two joined tables to have a
matching record.
Is this answer for outer join? or other standard way?
Thanks a lot!

w*r2008-08-22 07:08

13 楼

A full outer join B is equivalent to
A left join B
where B.* is null
union
A inner join B
union
A right join B
where A.* is null
got it?

【在 x****y 的大作中提到】

: outer join: retrieve both matching and non-matching rows. That is, outer
: join does not require each record in the two joined tables to have a
: matching record.
: Is this answer for outer join? or other standard way?
: Thanks a lot!

x*y2008-08-22 07:08

14 楼

这个是full outer join的表达/实现。我问的是面试时的语言表达。
我有对数据库的基本知识，但是，电话面试的语言表达不好。：（
还是谢一声：）

【在 w*r 的大作中提到】

: A full outer join B is equivalent to
: A left join B
: where B.* is null
: union
: A inner join B
: union
: A right join B
: where A.* is null
: got it?

w*r2008-08-22 07:08

15 楼

你就这么说，别人一定就明白了，而且还明白了你的集合论学得N好

x*y2008-08-22 07:08

16 楼

j*n2008-08-22 07:08

17 楼

remember last time I gave an example for outer join:
Say we have table A and B, A has 10 rows and B has 5 rows;
when do A left join B, the query returns total 10 rows including all from A,
data from B only returned what matches join condition, the non-matching part
is just null value.

【在 x****y 的大作中提到】

s*22008-08-22 07:08

18 楼

有包子　一定要顶　而且希望ＬＺ　能够把这工作搞定　　感觉你ＤＢ　还挺好的　哈
哈　　加油　　　您也踢球？
哪个州