SQL SERVER 2005 页面文件头部结构
Next up in the Inside the Storage Engine series is a discussion of page structure. Pages exist to store records. A database page is an 8192-byte (8KB) chunk of a database data file. They are aligned on 8KB boundaries within the data files, starting at byte-offset 0 in the file.
Here's a picture of the basic structure
Header
The page header is 96 bytes long. What I'd like to do in this section is take an example page header dump from DBCC PAGE and explain what all the fields mean. I'm using the database from the page split post and I've snipped off the rest of the DBCC PAGE output.
DBCC
TRACEON (3604)DBCC
PAGE ('pagesplittest', 1, 143, 1);GO
m_pageId = (1:143) m_headerVersion = 1 m_type = 1
m_typeFlagBits = 0x4 m_level = 0 m_flagBits = 0x200
m_objId (AllocUnitId.idObj) = 68 m_indexId (AllocUnitId.idInd) = 256
Metadata: AllocUnitId = 72057594042384384
Metadata: PartitionId = 72057594038386688 Metadata: IndexId = 1
Metadata: ObjectId = 2073058421 m_prevPage = (0:0) &
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数学函数
1.绝对值
S:select abs(-1) value
O:select abs(-1) value from dual
2.取整(大)
S:select ceiling(-1.001) value
O:select ceil(-1.001) value from dual
3.取整（小）
S:select floor(-1.001) value
O:select floor(-1.001) value from dual
4.取整（截取）
S:select cast(-1.002 as in ......
下面的这些脚本都可以找到引起磁盘排序的SQL。
SELECT /*+ rule */ DISTINCT a.SID, a.process, a.serial#,
TO_CHAR (a.logon_time, 'YYYYMMDD HH24:MI:SS') LOGON, a.osuser,TABLESPACE, b.sql_text
from v$session a, v$sql b, v$sort_usage c
WHERE a.sql_address = b.address AND a.saddr = c.session_addr;
......
select * from formtable_main_20
sp_help formtable_main_20
--drop view zcountQJ01
create view zcountQJ01
as
select appman ,year(startdata) as zyear,jb,cast(sum(num) as decimal(4,1) ) as num
from formtable_main_20
where year(getdate()) = year(startdata)
group by appman,jb,year(startdata) ......
SELECT * from user WHERE name LIKE '%三%';
将会把name为“张三”，“三脚猫”，“唐三藏”等等有“三”的全找出来；
在进行数据库查询时，有完整查询和模糊查询之分。
一般模糊语句如下：
SELECT 字段 from 表 WHERE 某字段 Like 条件
其中关于条件，SQL提供了四种匹配模� ......
题目要求
阿里baba的面试题
有三个表
学生表 S
SID SNAME
教师课表 T
TID TNAME TCL
成绩表 SC &n ......
