Programmer Group

1, Introduction to cursors 1. Introduction to cursors Cursor is a database query stored on MySQL server. It is not a select statement, but a result set retrieved by the statement. With the cursor, the result set can be processed row by row conveniently. The design of cursors is the idea of data buffer, which is used to store the results of S ...

To be honest, the definition of paging data source is too tedious, so it's encapsulated twice, without any intrusion, clean and neat. It's preserved for the time being, maybe it can be used in my life.. package com.lk.care.respository import androidx.paging.DataSource import androidx.paging.PageKeyedDataSource import androidx.paging.PagedList ...

summary: PL/SQL(Procedural Language/SQL) is a special application development language of Oracle database. It is a programming language formed after the process expansion of the standard SQL language. PL/SQL Oracle extends SQL procedure. PL/SQL database programming Benefits: simple, efficient, flexible and practical 1. Grammar Basic syntax: ...

Author: ksfzhaohui https://my.oschina.net/OutOfMemory/blog/3117737 Recently, there is a demand to analyze an order file, and the description file can reach tens of millions of data, each data is about 20 fields, each field is separated by commas, and it needs to be stored in half an hour as much as possible. thinking 1. Estimate file size Bec ...

1, Analysis function RANK the same value RANK the same, RANK jump DENSE_RANK the same value rank the same, rank consecutive ROW_NUMBER returns a sequential ranking, regardless of whether the values are equal or not The following figure is an example of three ranking methods --The following three analysis functions can be used for ran ...

pydbclib It is a general python relational database operation toolkit. It uses a unified interface to operate various relational databases (such as oracle, mysql, postgres, hive, impala, etc.) for addition, deletion, and query. It is a connection driver package for various python databases (such as sqlalchemy, pymysql, CX_ The encapsulation of ...

Purpose: The 192.168.100.20 server backs up the MySQL database on the 192.168.100.10 server. 1. Configure MySQL server 1) 100.10 MySQL server log in to MYSQL to create two databases [root@centos01 ~]# mysql -uroot -ppwd@123 mysql> create database liyanxin; mysql> create database wangzhaojun; 2) liyanxin database creates tables and write ...

problem SQL Server is deployed on multiple platforms (Windows,Linux and Container) in many enterprises. A solution that can support multiple platforms is needed to collect and display related monitoring indicators. I choose the popular monitoring display tool Grafana and monitoring indicator collection tool Telegraf to implement. This is also t ...

by Aurora Today, I'd like to introduce the model part of Django framework. The model is a simple and clear description of real data. It contains the necessary fields and behaviors for stored data. Django follows the DRY Principle. Its goal is that you only need to define the data model, and then you don't need to care about other miscellaneous ...

​ In this chapter, we started to formally build a big data environment, with the goal of building a stable big data environment that can be operated and monitored. We will use Ambari to build the underlying Hadoop environment, and use the native way to build Flink, Druid, Superset and other real-time computing environments. Use the combinatio ...