• Oracle database optimization skills (1)


    Oracle database optimization skills (1) 1. Join order in where clause In Oracle database, the execution order of where clause isBottom upAccording to this principle, the connection between tables must be written before other where conditions, and those conditions that can filter out the maximum number of records must be written before other where conditions […]

  • Summary of MySQL architecture


    Architecture *Connector: used to support the interaction between various languages and SQL, such as PHP, python, JDBC of Java; *Management services & Utilities: system management and control tools, including backup and recovery, MySQL replication, cluster, etc; *Connection pool: connection pool, which manages the resources to be buffered, including user password, permissions, threads, etc; *SQL interface: […]

  • A complete understanding of MySQL index optimization explain Encyclopedia


    1. MySQL logical architecture In the process of curd, you can’t avoid dealing with databases. Most businesses can’t do without the design of database tables and the writing of SQL. How can you make your SQL statements perform better? Let’s take a look at the logic architecture of MySQL as a whole The overall logic […]

  • It’s class notes


    1 do the basic page, first import the data, there are related dependencies, 8.1.1 change the configuration file first2.1 create a control class to manage all page requests。You can start the test. Let’s see if the basic page is completed.This is the interface that should be queried, and the next idea. Log management is a […]

  • Vue router source code analysis (2) design idea and code structure


    According to the execution process of vuerouter, we can understand its design idea through these three steps Step 1: when we create an instance of new vuerouter, we will parse the array corresponding to the incoming router attribute through deep traversal, and save it in a map. Each map corresponds to an element of the […]

  • Shaking list Api: Hottest video tiktok today


    Tiktok tiktok, tiktok, tiktok, Api, Api, jitter, voice, bullet screen comments, jitter, jitter, and jitter. Tiktok tiktok tiktok data, jitter data acquisition, live broadcast of shaking sound Titodata: professional short video data acquisition and processing platform. For more information, please contact:TiToData Massive data collection Collect 500 million pieces of data for customers every day Tiktok […]

  • About Oracle


    Common operations 1. View the creation table parameters Extract the complete DDL SELECT DBMS_METADATA.GET_DDL(‘TABLE’,’table_name’) FROM DUAL; 2. Specify the number of returned records select XXX from XXX where rownum 3. Query all the values of the specified column and display only a single record for each value Select needs to query the column name of […]

  • How to apply for free SSL certificate


    This note is used to record how to apply for a free SSL certificate. The validity period of the certificate applied through the method described in this article is only 30 daysthree months, please choose carefully. get ready There are many websites like this that provide free SSL certificate. The platform I choose here isFreeSSL.cn […]

  • Angular component (ngkeybardselect) – multiple selection by keyboard


    In the just concluded angular trading system project, there are several requirements that make me feel that it will take some time How to use the modal box of angular bootstrap more elegantly. Through the keyboard to achieve multi selection of Ctrl and batch selection of shfit. How to realize waterfall flow in angular I […]

  • Don’t know VO, Bo, Po, do, dto? This one is enough


    At present, the industrialization level of programming is getting higher and higher, and there are more and more various programming models, such as MVC, mmvc and so on. Together with these programming models, we need to understand a variety of object definitions, such as VO, Bo, Po, do, dto, etc. if we do not understand […]

  • Installing pycurl on MAC


    Pycurl is needed for Python development under Mac, but there are some problems in the installation process. After a lot of twists and turns, we finally succeeded. The specific steps are as follows. Make a record to avoid forgetting. Step 1 brew install openssl Step 2 pip3 uninstall pycurl Step 3 PYCURL_SSL_LIBRARY=openssl LDFLAGS=”-L/usr/local/opt/openssl/lib” CPPFLAGS=”-I/usr/local/opt/openssl/include” pip3 […]

  • Mysql, sqlserver and Oracle specify the number of returned records


    Recently, new contacts with SQL server and Oracle database found that the total number of specified return records is actually different from mysql Mysql:select XXX where XXX limit N Sqlserver: select TOP N XXX Oracle:select XXXX where rownum < (N+1) Note: In Oracle, rownum = n, only n = 1 is true, others are false. […]