📧 Triggers and database security Tip: The general content of this article: This experiment is from topics 7 to 10 of "Database Principles and Technologies" of Tsinghua University Press. 2. P396 on-line experimental questions 8. 3. P396 computer experiment questions 9 topics.
😁 Again, the old saying goes: the basic prin ...
Posted by qazwsx on Wed, 04 May 2022 20:06:17 +0300
The system has been in operation for many years. The database server has also been running for many years, and its performance is relatively old. The capacity of the SSD hard disk is only 250G. Under various demands, the disk of the current server is about to be insufficient. Therefore, the migration of this database was started.
Returns the automatic primary key
1. Transaction processing
What are things?
Transaction: The mechanism in the database to ensure the reliability of transactions. JDBC supports the concept of transactions in the database, and in JDBC, transactions are automatically committed by default.
There are two wa ...
Posted by pabs1983 on Wed, 04 May 2022 12:30:43 +0300
Database and table building
view the database
-- View all databases
[take mine as an example, the following are]
mysql> show databases; ±-------------------+ | Database | ±-------------------+ | information_schema | | mysql | | performance_schema | | sqlfortextbook | | studb | | sys | ±------------- ...
2. Operation database
2.1 operation database
2.2 column type of database
tinyint very small data 1 bytesmallint smaller data 2 bytesmediumint medium size 3 bytesint standard integer 4 bytesbigint larger datafloat floating point number 4 bytesdouble floating point number 8 bytesFinancial calculation of floating point num ...
Posted by grumpy on Tue, 03 May 2022 19:40:00 +0300
Multi table query, also known as association query, refers to two or more tables completing the query operation together
Prerequisites for multi table query
Basic syntax of multi table query
Classification of multi table query
Equivalent connection and non equivalent connection
Self connected and non self connected
Internal con ...
Posted by tanita on Tue, 03 May 2022 11:50:59 +0300
1, What is JDBC
When it comes to JDBC, we should first think of the 13 specifications in Java. One of them is JDBC. What is it and what is its use?
Let's take a look at Baidu Encyclopedia first
In short, it is the method of connecting the database with Java, but we all know that the Java language is developed and maintained by Oracle company, ...
Redis cache database foundation
Redis, remote dictionary service.
What can you do?
Data persistence: RDB, OF
High efficiency, cache
Publish subscribe system
Map information analysis
Timer, page views
Diverse data types
Things needed in learning
Redis official website: http ...
Posted by Studio381 on Sun, 01 May 2022 22:29:16 +0300
A transaction is a user-defined sequence of database operations. These operations are either done or not done at all, and are an inseparable unit of work.
Based on the atomicity, consistency, isolation and persistence characteristics of transactions, related data operations can be defined into a transaction.
If no exception occurs during the ...
Posted by wblati on Sat, 30 Apr 2022 23:02:23 +0300
Basic operation of MySQL database
1. Creation of database
1.1 create database
create database <Database name> -- stay sql Statements are not case sensitive
use <Database name>
drop database <Database name>
view the database
show databases <Database name>
1.2 crea ...