Programmer Group

1. Add, delete, modify and check. 1, For the add operation, if the id is generated automatically, the primary key needs to be returned. Note that if the primary key is of Long type, the int type should also be returned, because mybatis does not support Long.   mybatis ResultMap application My ...

1. Connect mysql Connect this machine mysql -u root -p Connecting to a remote host mysql -h 192.168.1.128 -u root -p Sign out exit; 2. Change password Format: alter user user name @ host address identified by 'new password'; Change the root password to newroot alter user root@local identified by 'newroot'; View user host add ...

In the previous article, we introduced the specified image file and added watermark to the specified file In this paper, watermark is applied to the project. When the user uploads the picture file, the corresponding watermark is added to the picture Still using a generic handler (. ashx) Users add pi ...

This post is a reference Lepus Official Documentation The official documentation was detailed, but some download links failed (maintainers of this open source product are busy, so updates are not timely) and the use of lepus was documented for their own writing style, so this post appeared. The Lepus system features are as follows: Remote mo ...

Note: Both commit() and execute() of database pymysql submit data synchronously to the database when submitting data. Because of the resolution of scrapy framework data and the asynchronous multi-threaded, scrapy's data resolution speed is much higher than the speed at which data is written to the database.If the data is writte ...

1. Briefly introduce that scrapy official documents have more code but fewer changes, while the second sends fewer codes but changes more. 1. The first method; the official document method.We can go to settings to copy the document web address into the official document for copy and paste.(Only three modifications are required ...

I usually like making python modules. Recently, I made a module "nss" (which is used for database) and I uploaded it to pypi. ... First, you can download this module with 'pip install nss'. Because the size of the module itself is relatively small and the download is relatively fast, it can be ...

Introduction and use of HBase 1, introduction hbase is the open source java version of bigtable. It is a database system based on hdfs, which provides high reliability, high performance, column storage, scalability, real-time reading and writing of nosql. 2. Differences with RDBMS 1. RDBMSStructur ...

original text Abridged slightly Alarm overview Prometheus alarms are divided into two parts. Alarm rules in Prometheus server send alarms to alert manager, which processes these alarms, including silence, inhibition, aggregation, and sending notifications through email, online notification system and ...

Foreign Key Management Foreign key concept If a public key is the primary key in a relationship, it is called the foreign key in another relationship.Thus, the foreign key represents the correlation between the two relationships.Tables whose primary key is a foreign key to another relationship are called primary tables, and tables with foreign ...