• SQL Server traverses data using table variables or temporary tables


    1. SQL script usageTable variablesTraversal data example: –Table variable 1 declare @tempTb Table(ID int, Name nvarchar(64)) –Table variable 2 declare @DtTb Table(ID int, Name nvarchar(64)) insert into @DtTb select top 100 ID,Name from [dbo].[Students] –Declare the variable of the loop declare @ID int; –Loop through ID while exists(select ID from @DtTb) begin Set rowcount 1; […]

  • [20201204] why to return 2 rows of records.txt


    [20201204] why to return 2 rows of records.txt –//In itpub, http://www.itpub.net/thread-2140116-1-1.html . It took a little time to figure out what the problem was,–//The problem is the consistency read, refer to the link http://blog.itpub.net/267265/viewspace-2213824/ =>[20180907] accessing V $view and consistent reading.txt [email protected]> @ ver1 PORT_STRING                    VERSION        BANNER—————————— ————– ——————————————————————————–x86_64/Linux 2.4.xx       Oracle Database 11g Enterprise […]

  • Browser side storage you need to know


    What is it? Web storage is a data storage mechanism provided by HTML5 for browser storage. It is divided into local storage, session storage and indexdb Why? Large storage capacity: according to different browsers, the storage capacity of web storage can reach 5-10m. It is only located in the browser side and does not communicate […]

  • Transaction isolation level of MariaDB


    In the last article, we talked about MariaDB’s locks, and how to manually lock and unlock them. Please refer to the review https://www.cnblogs.com/qiuhom-1874/p/13196905.html Today, let’s talk about the transaction isolation level of MariaDB. In the previous essay, we mentioned the storage engine of MySQL, including MyISAM and InnoDB, where MyISAM does not support transactions and […]

  • Cookie of Django web development


    1、 Cookie 1.1 what is a cookie? A cookie is a small piece of text information generated by the server and stored in the browser.Characteristics of Cookie:1) WithKey value pairIt can be stored in different ways.2) When you visit a website through a browser, all cookie information related to the website stored in the browser […]

  • Oracle operation and maintenance — 07. View lock resources


    1. Check the table locking condition; SELECT /*+ RULE */ Ls.Osuser Os_User_Name, Ls.Username User_Name, Decode(Ls.TYPE, ‘RW’, ‘Row wait enqueue lock’, ‘TM’, ‘DML enqueue lock’, ‘TX’, ‘Transaction enqueue lock’, ‘UL’, ‘User supplied lock’) Lock_Type, o.Object_Name OBJECT, Decode(Ls.Lmode, 1, NULL, 2, ‘Row Share’, 3, ‘Row Exclusive’, 4, ‘Share’, 5, ‘Share Row Exclusive’, 6, ‘Exclusive’, NULL) Lock_Mode, o.Owner, […]

  • How to use the screen command


    Hello, I’m Liang Xu. Most of the time, we need to perform some tasks that take a long time. If your network connection is suddenly disconnected at this time, all the work you have done before may be lost, and all the work you have done may have to be done again, which will waste […]

  • 04 – Fiddler


    Fiddler can not only intercept HTTP requests from various browsersIt can also intercept http / HTTPS requests from various smart phones. Fiddler can capture requests from IOS devices, such as iPhone, iPad, macbook, etc. In the same way, you can also intercept http / HTTPS sent by Android, Windows Phone and other devices. working principle […]

  • Password based cryptography (PBE)


    Password based cryptography (PBE) Password based encryption (PBE) is a method of generating key based on password and using the key to encrypt. Encryption and decryption use the same key. According to the user’s own password and salt generated password, let’s first look at the encryption process: The encryption process can be divided into the […]

  • MySQL variable description


    #Variable #1、 System variables #1》 Global variables #① View all global variables SHOW GLOBAL VARIABLES; #② View some system variables that meet the conditions SHOW GLOBAL VARIABLES LIKE ‘%char%’; #③ View the value of the specified system variable SELECT @@global.autocommit; #④ Assign a value to a system variable SET @@global.autocommit=0; SET GLOBAL autocommit=0; #2》 Session […]

  • PHP session_ cache_ Expire session function


    Definition and Usage session_cache_expire– returns the expiration time of the current cache grammar session_cache_expire ( [ string $new_cache_expire ] )    session_cache_expire()Return session.cache_ The set value of expire. When the request starts, the cache expiration time is reset to 180 and saved in the session.cache_ Expired configuration item. Therefore, for each request, thesession_start()Call before function […]

  • MySQL lock mechanism


    Interior lock MySQL performs internal locking within its own server to manage contention for table content by multiple sessions. Internal lock can be divided into row lock and table lock. External lock MySQL provides options for client sessions to explicitly acquire table locks to prevent other sessions from accessing tables. You can use the lock […]