This article mainly introduces the summary of practical commands for using percona-toolkit to operate MySQL. percona-toolkit is a powerful MySQL auxiliary tool. For more information, see
1.pt-archiverFunction introduction:
Archive the records of tables in the mysql database to another table or file
Usage:
Pt-archiver [OPTION...] -- source DSN -- where WHERE
This tool only archives old data and does not significantly affect OLTP query of online data. you can insert the data into other tables on a
; Bread = ["1"]>>> Hotdog = ["0", "1"]>>> Mustard = ["0", "1"]>>> Onion = ["0", "1"]>>> Combination = []>>> For B in bread:... For h in hotdog:... For t in tomato_jam:... For m in mustard:... For o in onion:... Combination. append (B + h + t + m + o)...>>> Print combination['123', '123', '123', '123', '
Chown to change the main or owning group of a fileChange file owner: #chown Zek 123.txt (Zek is the name of the owner)#ls-L 123.txt-rw-rw-rw-1 Zek Root 12777 December 4 20:31 123.txtChange file to group such as: #chown: User1 123.txt# ls-l 123.txt-rw-rw-rw-1 Zek user1 12777
statement in else is executed.i = 0 while I : print(i) + = 1else: Print ('i equals 5') output result: 01234i equals 5FunctionFirst, create a function 1, create a function of the basic formatdef function name (formal parameter): function Body return"123" Second, the return value of the functionAfter the function executes a return, the following code is no longer executed, and the returned value is given to the variable assigned afte
Tags: Web server knowledge products Getting started with the old Boys database01-old boy Maintenance DBA course classes650) this.width=650; "src=" Http://s1.51cto.com/wyfs02/M00/80/42/wKioL1c8XungiEs3AAst3qOyO4A715.png "title=" 123. PNG "alt=" Wkiol1c8xungies3aast3qoyo4a715.png "/>02-Introduction to Database ConceptsFrom the architecture to solve the bottleneck of the database explained a truth, there are problems do not resist, to team spirit, the da
Write the annotation conversion program to implement the conversion function of annotations in a C + + language program source file1.c++ style comments//notes converted to standard C-style */*/comments2./* * * Style comments remain the same3. All conversions are subject to grammatical rules4. Annotation transformations need to support comment nestingNote Conversion requirements:There are a lot of nesting cases for annotations, and here's just an example, you need to follow the code of the C + +
Throughout China's Internet 50 segments (according to the 2007 China Internet Survey Report "see the attachment"), the market concentration of website navigation is not very high, so the entry threshold is also reduced. However, website navigation websites are also starting to be subdivided, such as specialized regional website navigation and specialized e-commerce navigation websites. Although there are currently 0.13 billion of Internet users in China, and this number is still gr
BETWEEN OperatorThe BETWEEN operator... AND selects a data range BETWEEN two values. This
Some values can be numerical values, text values, or dates.
SQL BETWEEN SyntaxSELECT WHERE (
Mysql tutorial>Mysql> create table Employee (-> Id int,-> First_name VARCHAR (15 ),-> Last_name VARCHAR (15 ),-> Start_date DATE,-> End_date DATE,-> Salary FLOAT (8, 2 ),-> City VARCHAR (10 ),-> Description VARCHAR (15)-> );Query OK, 0 rows affected (0.05 sec)
Mysql>Mysql>Mysql> insert into Employee (id, first_name,
], [descript] [nvarchar] (10 ))
Insert into [TB]
Select '123', '123', 'Lee Sun Tzu 'Union all
Select '123', '123', 'old Wang sons' Union all
Select '123', '123', 'old Zhang sons' Union all
Select '
Answer reference:Suppose there are variablesvar=http://www.oldboyedu.com/123.htm.1. # Intercept, delete the left character, leave the right character.Variable: Var=http://www.oldboyedu.com/123.htmecho ${var#*//} where Var is the variable name and the # is an operator, *//means to delete the first//number and all characters on the left from the left to remove http://The result is : www.oldboyedu.com/
ECMA-262 (E3) did not write the JSON concept to the standard, fortunately the concept of JSON in ECMA-262 (E5) was formally introduced, including the global JSON object and the Tojson method of date.1,eval way to parse, I am afraid this is the earliest way to parse. As follows:Copy CodeThe code is as follows:function Strtojson (str) {var json = eval (' (' + str + ') ');return JSON;}Remember to do not forget the parentheses on both sides of Str.Here the property name can use a number, can be quot
, if the second one is the same, then compare the third place ... Accordingly, in "Example 1" if "LSS"In the "4" statement, the essence is 1 and 4 comparison, 1 of course less than 4, so executed the following command: Echo 12 unexpectedly less than 4 oh?
☆ Suggest: If it is a string comparison use double quotes "" is the comparison of numbers without double quotes!------------------------------------------------------------------------------------------------------
3. Judge whether a drive, f
deleting keys, and manipulating arrays and inline documents$set: Used to specify a value for a field. If this field does not exist, it is created.Db.foo.update ({"_id": "123"},{"$set": {"NB": "New Baby"}});if the "NB" field does not exist, a "NB" field is created and the "NB" field value is updated instead. The $set can even modify the type of the key. as follows:Db.foo.update ({"_id": "123"},{"$set": {"N
Touch create file or update file timestampFormat: Touch parameter file nameParameters:-C: Do not create a file that does not exist-M: Update only modified time, not update access time-A: Update access time only, not update modification time-R file: Time to update files using file files-T: Modifies the time to the date specified by the parameter, such as 01091135 for January 9 11:35Additional Knowledge: View file information (created date): Ls-l View file information (access date): Ls-lu[[emailpr
1 Preface
If you are familiar with the WTL or CString standard of the Cstring,windows Template Library (Template) of Microsoft Foundation Classes (MFC) Library (STL) String class, then you must be familiar with the String.Format method. This method is often used in C # to format strings, such as the following:
int x =;
Decimal y = 3.57m;
String h = String.Format ("Item {0} sells at {1:c}", X, y);
Console.WriteLine (h);
On my machine, I can get the following output:
Item sells at¥3
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