hecker stuff

This is a note for the exam.　　MV command can be moved can be renamed1 MV a/test // move A To test folder 2 mv a b // rename A to B　Soft links and hard-link creation1 ln-s profile a //profiles Create a soft link a2 ln /b// profile file creates a hard link BFind Files1 Find NewFile // Find files with name NewFileCompiling the C language code1 vim hello.c // I have written a C language file 2 gcc-g hello.c-o a // Compile this file into a3 ./a

descendant selector. David Hyatt: The descendant selector is the most expensive selector in CSS and is prohibitively expensive-especially if it is behind a label and a generic character.As the following this dongdong, absolute efficiency cancer: The following are the referenced contents:HTML Body ul li a {} A selector render failure is more efficient than this selector is rendered I'm not quite sure if there's any better evidence to prove it, because if you have a l

' ( You will find that the SQL Ming is fast!

Label:Today in the work encountered the following this problem, you need to make the following query results, stitching into one line! 1 Select person_name from S_project_member where project_id = ' 2c9081473e2f8bda013e3028e4700049'; Let's go straight to the code! -------------------------have problems, please point out-------------------------------------------------------- Select CAST(Stuff(( Select distinct ','+Person_name fromS

is recommended to manually arrange them beforehand.**************************************************6. In some cases the in function is equivalent to or, and neither can fully utilize the indexExample: Table stuff has 200000 rows, id_no on the non-clustered index, see the following sql:Select COUNT (*) from stuff where id_no in (′0′,′1′) (23 seconds)We expect it to look for each or clause separately, and

user S1 permission to update on the Sle_course table and allow him to propagate the permissionGrant UPDATE on TABLE sle_course to S1 with GRANT OPTION;After S1 obtains this permission, he can grant this permission to S2.GRANT UPDATE on TABLE sle_course to S2;Example 3:DBA will grant S3 the permission to establish a base table in the database pubs.GRANT Creattab on the DATABASE pubs to S3;Reclaim PermissionsNote: When more than one user is involved in propagating permissions, the permission of t

First we have a table query result as follows:Now we want to put the contents of the User_name column in a field:A row of SQL statements resolves the issue:Select STUFF ((select ', ' +convert (VARCHAR, user_name) from Te_user for XML PATH (")), 1, 1, ') as UserNameExplain the above statement:1, first stuff function in the above statement is to remove the concatenation of the front of the string commaThe u

QUOTED_IDENTIFIER ON GO Create procedure [dbo]. [My_Search_StringInGivenTable] (@ SearchString NVARCHAR (MAX ), @ Table_Schema sysname, @ Table_Name sysname) AS BEGIN DECLARE @ Columns NVARCHAR (MAX), @ Cols NVARCHAR (MAX), @ PkColumn NVARCHAR (MAX) -- Get all character columns SET @ Columns = STUFF (SELECT ',' + QUOTENAME (Column_Name) FROM INFORMATION_SCHEMA.COLUMNS WHERE DATA_TYPE IN ('text', 'ntext', 'varchar ', 'nvarchar', 'Char ', 'nchar ') AND

--- SELECT * FROM (SELECTDISTINCTcolumn1FROMtable1) Explain ssapply (SELECTcolumn2 (SELECT [*] column2FROMtable1WHEREcolumn1A. column1FORXMLPATH (), TYPE ). value (, nvarchar (20) B ---- SELECT * FROM (SELEC --- First SELECT * FROM (select distinct column1 FROM table1) a cross apply (SELECT column2 = (SELECT [*] = column2 FROM table1 WHERE column1 =. column1 for xml path (''), TYPE ). value ('/', 'nvarchar (20) ') B ---- SELECT * FROM (SELEC --- First SELECT * FROM (select distinct column1 F

design is too obvious, you may not pay enough attention to other optional methods. To help you break away from the habitual path of object-oriented design, we will consider other methods to solve this problem. The template method pattern via the non-virtual interface idiom (the template method mode is implemented through non-Virtual Interface Usage) We started with an interesting idea that virtual functions should almost always be private. Advocates of this view suggested that a better design s

Peterson; will Poole; Brian Valentine; anoop Gupta (Research)Subject:Windows usability systematic degradation flame I am quite disappointed at how Windows usability has been going backwards and the program management groups don't drive usability issues. Let me give you my experience from yesterday. I decided to download (moviemaker) and buy the digital Plus Pack... so I went to Microsoft.com. They have a download place so I went there. The first 5 times I used the site it timed out

of a specified substring in a string.Patindex (Unlike the charindex function, wildcards can be used in the child strings of the patindex function, which can be used for char, varchar, and text data types. V. String operation functions1. quotename ()Returns a string enclosed by a specific character.Quotename ( 2. Replicate ()Returns a character string that repeats character_expression for a specified number of times.Replicate (character_expression integer_expression) if the value of integer_expr

@ updatefields = STUFF (@ updatefields, LEN (@ updatefields), 1 ,'') -- Save Conditions Declare @ tempwhere varchar (200) Set @ tempwhere ='' -- If conditions exist, the conditions are also processed in the same way. If (@ where! = '') Begin Declare @ oldwhere varchar (200), @ tempfield varchar (50) Set @ where = REPLACE (@ where ,',',',') If (right (@ where, 1 )! = ',') Set @ where = @ where + ',' Set @ oldwhere = @ where Set @ where ='' -- Travers

Motherboard chipsets and the memory map I'm going to write a few posts about computer internals with the goal of explaining how modern kernels work. I hope to make them useful to enthusiasts and programmers who are interested in this stuff but don't have experience with it. the focus is on Linux, windows, and Intel processors. internals are a holobby for me, I have written a fair bit of kernel-mode code but haven't done so in a while. this first post

As mentioned before, the internal function of the decorator has replaced the original function (new function), so this function will missing many attributes. 1 def is_admin(f): 2 def wrapper(*args, **kwargs): 3 if kwargs.get(‘usrename‘) != ‘admin‘: 4 raise Exception("Now allow") 5 return f(*args, **kwargs) 6 return wrapper 7 8 def foobar(username="soneone"): 9 """ DOcarzy stuff """10 pass11 12 13 >>> foob

function is not properly checked (checking whether callback is a function or passed in by argument), our code will cause a run-time error.Problems with the callback function that contains this objectWhen the callback function is a method containing the This object, we must modify the method that executes the callback function to protect the contents of this object. Otherwise the This object will point to the Global Window object (if the callback function is passed to the global function), or to

Copy Code code as follows: One DECLARE @s varchar (20) DECLARE @i varchar (20) Set @i= ' Set @s= ' new member must purchase 350 Yuan product ' While PATINDEX ('%[0-9]% ', @s) >0 Begin Set @i=@i+substring (@s,patindex ('%[0-9]% ', @s), 1) Set @s=stuff (@s,1,patindex ('%[0-9]% ', @s), ') End Select @i -- 300 Two: Declare @a table (ID int identity (1,1), a varchar (100)) Insert @a Select ' new member must purchase 3

Wget is a very useful Internet download tool, he has many features that other tools can not match, and he is a lightweight configurable download tool. This article combines examples to introduce the various downloading methods and uses of wget under Windows. 1. Download a single file with wget The download will show: ~ File size, connection status, connection address, and file size ~ Saved by name ~ Download progress bar ~ Download speed, time, and how many have not been downloaded For example,

); } If the GetInput function does not do an appropriate check (check that the callback is a function, or whether it is passed in through a parameter), our code will cause a run-time error. Problem with a callback function that contains the This objectWhen the callback function is a method that contains the this object, we must modify the method that executes the callback function to protect the contents of this object. Otherwise the This object will point to the Global Window object (if t

everything we can to make this famous "Hello World" example. RELATED LINKS in this chapter: Starterkit JQuery Downloads Hello JQuery Before we do everything, we want jquery to read and process the DOM of the document, we have to start executing the event as soon as possible after the DOM is loaded, so we use a ready event as the beginning of the processing of the HTML document. Look at the file we opened custom.js. : $ (document). Ready (function () { //do