Programmer Group

Simple query Select several tuples in the tableSelect several columns in the tableorder by clausegroup by clauseAggregate function Select several columns in the table Query the student number and name of all students select sno,sname from student Select several rows in the table Eliminate rows with duplicate values DISTINCT Query the stu ...

JDBCTemplate JDBC template (concept and preparation) What is a JdbcTemplate The Spring framework encapsulates JDBC and uses JdbcTemplate to facilitate database operation preparation Introduce related jar packages [the external chain image transfer fails. The source station may have an anti-theft chain mechanism. It is recommended to ...

Spring transaction management 1. Business What is a transaction A set of operations either succeeded or failed Characteristics of transactions ACID Atomicity, a group of operations is a whole, either all successful or all failed, and cannot be separatedConsistency: the data is consistent before and after the transactionIsolation: multipl ...

Continuous Learning & Continuous Updating... Learning Attitude: Keep away Basic Commands If you are prompted for Denial of Service when you enter a command, open the command prompt interface as a system administrator and try again Start MySQL Service Command net start MySQL service name Stop MySQL Service Command net stop ...

This article is based on TiDB release-5.1 and needs to use versions after Go 1.16 My blog address: https://www.luozhiyun.com/archives/631 The so-called Hash Join is to select a table as the buildSide table to construct the hash table and another table as the probeSide table when joining; Then, for each row of data in the probeSide table, go to ...

Index and transaction 🎈🎆🎇 preface: This post only introduces the principles and concepts, not the specific underlying implementation 1, Index 1.1 what is an index How to find the target quickly when the number in the database is huge? The index is used. If a book wants to quickly find the knowledge points it wants, it will firs ...

catalogue MySQL master-slave replication         Master slave replication architecture and principle                   Function of replication                 Replication schema     ...

1. C3P0 database connection pool Information: link: https://pan.baidu.com/s/19jWfIQ_OlZ29pPPnxNm5og Extraction code: hgha 1.1 concept In fact, it is a container (Collection) for storing database connections.After the system is initialized, the container is created, and some connection objects will be applied in the container. When the user a ...

1, select basic syntax The select statement is used to select data from the database. The results are stored in a result table called a result set. Quotation marks and semicolons in the select query statement are English symbols, and the end flag of the query statement is semicolon. Take dept table as an example to demonstrate: Descr ...

catalogue 1, MySQL master-slave replication 1. Principle of master-slave replication 1. Replication types supported by MySQL 2. Working principle of MySQL master-slave replication 3.MySOL master-slave replication delay 4. Role of replication 2. Specific operation 1. Main server 192.168.68.200 2. From server 192.168.68.30 3. From serve ...