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 several rows in the table
Eliminate rows with duplicate values DISTINCT Query the stu ...
Posted by hobeau on Mon, 06 Dec 2021 21:52:17 -0800
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 ...
Posted by samsunnyuk on Mon, 06 Dec 2021 20:53:20 -0800
Spring transaction management
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 ...
Posted by romic on Mon, 06 Dec 2021 20:52:09 -0800
Continuous Learning & Continuous Updating...
Learning Attitude: Keep away
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 ...
Posted by gnathan87 on Mon, 06 Dec 2021 09:01:00 -0800
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 ...
Posted by adeelahmad on Sun, 05 Dec 2021 21:30:21 -0800
Index and transaction
This post only introduces the principles and concepts, not the specific underlying implementation
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 ...
Posted by Unforgiven on Sun, 05 Dec 2021 14:12:33 -0800
1. C3P0 database connection pool
Information: link: https://pan.baidu.com/s/19jWfIQ_OlZ29pPPnxNm5og Extraction code: hgha
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 ...
Posted by waltonia on Sun, 05 Dec 2021 07:34:12 -0800
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 ...
Posted by pella.d on Sun, 05 Dec 2021 05:04:57 -0800