The undo mechanism is a clever feature of Oracle and one of the difficulties in learning oracle.
Next we will learn more about it internally.
Session 1: Scott user, initiates a transaction
hr@ORCL> conn scott/oracleConnected.scott@ORCL> UPDATE emp SET sal=4000 WHERE empno=7788;1 row updated.scott@ORCL> SELECT empno,ename,job,mgr,sal FROM emp WHERE empno=7788; EMPNO ENAME JOB MGR SAL---------- ---------- --------- ---------
-- Exchange of rows and columns/*************************************** **************************************** **************************************** *******************************Take student scores as an example, which is easy to understand
Organized by: Roy)
Date: 2008.06.06**************************************** **************************************** **************************************** ******************************/
-- 1. Columns of rows--> (Roy) generate a sequence numberIf no
, nvarchar, and ntext. The three names are named N more than the first three ". It indicates that characters of the Unicode data type are stored. We know that only one byte is required for English characters, but there are many Chinese characters and two bytes are required for storage. It is easy to cause confusion when both English and Chinese characters exist,Unicode Character Set is generated to solve the incompatibility problem of character sets. All its characters are expressed in two bytes
value. That is, the interval range of each box is a constant called the box width.
User-defined intervals: You can customize intervals as needed. This method can be used to help you easily observe the data distribution within certain intervals.
For example, the value of the customer's income attribute income after sorting (RMB): 800 1000 1200 1500 1500 1800 2000 2300 2500 2800 3000 3500 4000 4500. The binning result is as follows.
Uniform weight: Set
()
'Do something here
End Sub
End Class
Subprograms and functions are called methods. Method naming also follows the naming rules of Pascal.
Another type of member is a domain. Domain naming rules follow the camel rules, that is, the first letter of all substrings except the first substring is capitalized. Like salary and quarterlyBonus are domain names that comply with the rules. The following code adds the salary and quarterlyBonus fields to the Employee class:
Added two fields of the Employe
destination 192.168.1.2 0 time-Range Test
[H3C-acl-adv-3000] Quit
(3) apply ACL on the port
# Apply ACL 1/0 to port ethernet 3000/1.
[H3C] interface ethernet1/0/1
[H3C-Ethernet1/0/1]QoS
[H3C-qoss-Ethernet1/0/1] packet-filter Inbound IP-group 3000
(1) define a time period
# Defines the period from.
[H3C] Time-range test8: 00 to 18: 00 daily
(2) define ACL rules for Mac 000f-e20f-0101 destination: 000f-e20f-0303
# Access the ACL 4000 View
[H3C] ACL n
Create procedure getrecordfrompage@ Tblname varchar (255), -- table name@ Fldname varchar (255), -- field name@ Pagesize Int = 10, -- page size@ Pageindex Int = 1, -- page number@ Iscount bit = 0, -- returns the total number of records. If the value is not 0, the system returns@ Ordertype bit = 0, -- set the sorting type. If the value is not 0, the sorting type is descending.@ Strwhere varchar (4000) = ''-- Query condition (Note: Do not add where)As
D
Recently established in the lab's network environment, all host labs are connected via a switch. Want to be a gateway through the server (single card), using the Mentohust authentication extranet, and then other hosts in the intranet through this gateway to connect to the external network.1. First use mentohust on the server to connect to the extranet, and then enter the Ifconfig command at the terminal to view the acquired extranet IP:Eth0 Link encap: Ethernet Hardware address B8:AC:6F:D8
, there's a shorter version.This code is what I wrote in Cn-dos, and today it's a little more streamlined.The code's algorithms go deep into the first layer:Use HMSW (each letter represents a two-digit number) to indicate the standard timeWe'll keep him in the wee hours. The number of relative time is TXTX=HMSW time Point -0:00:00.00 time Point =h*3600*100+m*60*100+100*s+wHMSW 8-bit 10-digit number of times (in 0.01 seconds) is hmsw run secondsHmsw=w+100*s+10000*m+1000000*hHmsw-tx=640000*h+
.-SDonotshowconfidenceestimators andwarnings.-gfilenameoutputcollecteddatatognuplotformat File.-efilenameoutputcsvfilewithpercentagesserved-hdisplay usageinformation (thismessage) #-attributes set the properties of the string . the bug program has various statically declared fixed-length buffers. In addition, parsing of command-line arguments, the response headers of the server, and other external inputs can be very simple, which may have undesirable consequences. It does not fully implement HTT
contents of six fields with SQL statements, and display them as a new field, see Code for implementation:
Copy Code code as follows:
#region selects Questionid,chapterid,questiontypeid,point from the table according to the dynamically generated database table name, excluding difficulty level constraints
Select Questionid,chapterid,questiontypeid,point from the table, based on the dynamically generated database table name.
Degree,fraction,questioincontent,isvalid and other content
Copy Code code as follows:
--function
CREATE function fn_getpy (@str nvarchar (4000))
Returns nvarchar (4000)
--with encryption
As
Begin
DECLARE @intLenint
DECLARE @strRetnvarchar (4000)
declare @temp nvarchar (100)
Set @intLen = Len (@str)
Set @strRet = '
While @intLen > 0
Begin
Set @temp = '
Select @temp = case
When substring (@str, @intLen
first stage, try slideshow
In doing a Web page homepage, want to use slideshow[1] do picture switching effect, which JS part of the code as follows:
Copy Code code as follows:
function Next_slide () {
var $active = $ (' #bitware-overlay img.active ');
if ($active. length = 0)
$active = $ (' #bitware-overlay img:last ');
var $next = $active. Next (). length? $active. Next (): $ (' #bitware-overlay img:first ');
$active. addclass (' last-active ');
$next. addclass (' a
(4000)
Set @s= '
Select @s=@s+ ', ' +quotename ([Course]) + ' =max (case when [course]= ' +quotename ([Course], ' "') + ' then [Score] else 0 end) '
From Class group By[course]
EXEC (' SELECT [Student] ' +@s+ ' from Class Group by [Student] ')
Generate Static:
Select
[Student],
[Math]=max [course]= ' math ' then [Score] else 0 end),
[Physical]=max [course]= ' physical ' then [Score] else 0 end),
[English]=max [course]= ' English ' then [Score] els
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