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We may often use Hibernate, Mybatis, jpa and other frameworks in our study and work. These frameworks have a good encapsulation of the database connection pool and may ignore the underlying implementation of the database. Today, let's take a look at how to write a simple database connection pool. Before that, let's recall the steps of ja ...

catalogue 1, Introduction to ELK log analysis system 1. Advantages and disadvantages of log server 2. What is ELK? 2.1 Logstash management includes four tools 2.2 log processing steps   2, Basic core concepts of Elasticsearch 3, Logstash introduction 4, Introduction to Kibana 5, Configure ELK log analysis system 1. Install elasti ...

Multi table query, also known as association query, refers to two or more tables completing the query operation together. Prerequisite: these tables queried together are related (one-to-one, one to many). There must be an associated field between them. This associated field may or may not have a foreign key. For example, employee table a ...

All the code in this article is big root heap! The implementation language is Java The pictures are all from the great God, and the great God's articles also give me a lot of inspiration Heap of data structures Heap sort This video is easy to understand, from what is heap, what is heap, and then to the realization of heap sorting. It is ver ...

Wan A10: how does mysqldump achieve consistent backupExperimental sceneMySQL 8.0.25 InnoDBExperimental steps:Start general first_ Log observe the changes in the export execution processset global general_log=ON;mysqldump key parameter description:--Single transaction parameter description:Set the isolation level to REPEATABLE READ and start a r ...

Advanced 1. Direct query – single field in query table – select sNo from student; – single field in query table – select sNo, sName from student; – query all fields in the table select * from student; Note: which library to use when querying all fields 2. Query constant value select 100; select 'male'; ...

1. View A view is a virtual table, which is different from a direct operation data table. A view is created based on a SELECT statement (which will be described in detail below). Therefore, when operating a view, a virtual table will be generated according to the SELECT statement that created the view, and then SQL operations will be performed ...

1, How many constraints do you master in MYSQL? In MYQSL, there are some constraints. For example, it cannot be null or must be unique. Like ID cards, everyone's ID number is unique. Gender can be male or female, but not null. The following describes six constraints in MYSQL 1. NOT NULL: a constraint column cannot be empty. -- Cre ...

Part 1: init initializes MySQL connection related API s: (1) mysql_init : MYSQL* mysql_init(MYSQL *mysql); Returns a MySQL handle. Corresponding to this handle, MySQL will allocate an object in the database and open up memory to store the processing information associated with the connection. All subsequent operations on this database conne ...

An important basic work in data governance is to analyze the blood relationship of data in the organization. With complete data kinship, we can use it for data traceability, impact analysis of table and field changes, proof of data compliance, inspection of data quality, etc. The methods of analyzing blood relationship of data are mainly divid ...