MindMap Gallery MySQL_01 Database Overview
📌 A guide to a new database, quickly master the core concepts! This article deeply analyzes the core role of database management system (DBMS), discusses the difference between relational database (RDBMS) and non-relational database (NoSQL), and explains the rules of relational database design to help you build efficient data structures. Whether you are a database beginner or want to strengthen the basics of database knowledge, this article is worth reading! 🚀
Edited at 2025-03-04 11:07:30Rumi: 10 dimensions of spiritual awakening. When you stop looking for yourself, you will find the entire universe because what you are looking for is also looking for you. Anything you do persevere every day can open a door to the depths of your spirit. In silence, I slipped into the secret realm, and I enjoyed everything to observe the magic around me, and didn't make any noise. Why do you like to crawl when you are born with wings? The soul has its own ears and can hear things that the mind cannot understand. Seek inward for the answer to everything, everything in the universe is in you. Lovers do not end up meeting somewhere, and there is no parting in this world. A wound is where light enters your heart.
Chronic heart failure is not just a problem of the speed of heart rate! It is caused by the decrease in myocardial contraction and diastolic function, which leads to insufficient cardiac output, which in turn causes congestion in the pulmonary circulation and congestion in the systemic circulation. From causes, inducement to compensation mechanisms, the pathophysiological processes of heart failure are complex and diverse. By controlling edema, reducing the heart's front and afterload, improving cardiac comfort function, and preventing and treating basic causes, we can effectively respond to this challenge. Only by understanding the mechanisms and clinical manifestations of heart failure and mastering prevention and treatment strategies can we better protect heart health.
Ischemia-reperfusion injury is a phenomenon that cellular function and metabolic disorders and structural damage will worsen after organs or tissues restore blood supply. Its main mechanisms include increased free radical generation, calcium overload, and the role of microvascular and leukocytes. The heart and brain are common damaged organs, manifested as changes in myocardial metabolism and ultrastructural changes, decreased cardiac function, etc. Prevention and control measures include removing free radicals, reducing calcium overload, improving metabolism and controlling reperfusion conditions, such as low sodium, low temperature, low pressure, etc. Understanding these mechanisms can help develop effective treatment options and alleviate ischemic injury.
Rumi: 10 dimensions of spiritual awakening. When you stop looking for yourself, you will find the entire universe because what you are looking for is also looking for you. Anything you do persevere every day can open a door to the depths of your spirit. In silence, I slipped into the secret realm, and I enjoyed everything to observe the magic around me, and didn't make any noise. Why do you like to crawl when you are born with wings? The soul has its own ears and can hear things that the mind cannot understand. Seek inward for the answer to everything, everything in the universe is in you. Lovers do not end up meeting somewhere, and there is no parting in this world. A wound is where light enters your heart.
Chronic heart failure is not just a problem of the speed of heart rate! It is caused by the decrease in myocardial contraction and diastolic function, which leads to insufficient cardiac output, which in turn causes congestion in the pulmonary circulation and congestion in the systemic circulation. From causes, inducement to compensation mechanisms, the pathophysiological processes of heart failure are complex and diverse. By controlling edema, reducing the heart's front and afterload, improving cardiac comfort function, and preventing and treating basic causes, we can effectively respond to this challenge. Only by understanding the mechanisms and clinical manifestations of heart failure and mastering prevention and treatment strategies can we better protect heart health.
Ischemia-reperfusion injury is a phenomenon that cellular function and metabolic disorders and structural damage will worsen after organs or tissues restore blood supply. Its main mechanisms include increased free radical generation, calcium overload, and the role of microvascular and leukocytes. The heart and brain are common damaged organs, manifested as changes in myocardial metabolism and ultrastructural changes, decreased cardiac function, etc. Prevention and control measures include removing free radicals, reducing calcium overload, improving metabolism and controlling reperfusion conditions, such as low sodium, low temperature, low pressure, etc. Understanding these mechanisms can help develop effective treatment options and alleviate ischemic injury.
Chapter 01_Database Overview
1. Database and Database Management System
1.1 Related concepts of databases
DB: Database, a repository for storing data, is essentially a file system.
DBMS: Database Management System, a large-scale software that manipulates and manages databases. It is used to establish, use and maintain databases and manages and controls the databases in a unified manner. Users access data in tables in databases through the database management system.
SQL: Structured Query Language, a language used to communicate with databases.
2. RDBMS and non-RDBMS
2.1 Relational Database
2.1.1 Substantive
The relational number library model involves forming complex data structures into simple binary relationships (two-dimensional tabular form).
Relational databases store data in the form of rows and columns. This series of rows and columns are called tables. A set of tables forms a database.
There is a relationship between the data records between the table.
SQL is the query language for relational databases.
2.1.2 Advantages
Complex query: SQL statements can be used to easily make very complex data queries between one table and multiple tables.
Transaction support: enables the implementation of data access requirements with high security performance.
2.2 Non-relational database (non-RDBMS)
Non-relational databases can be regarded as a castrated version of traditional relational database functions. They store data based on key-value pairs, and do not need to be parsed by the SQL layer, and have very high performance.
A key-value database stores data through the Key-Value key-value method.
Document-type database, which can store and obtain documents, can be in XML, JSON and other formats.
Search engine database, a data storage form applied in the search engine field, is the core principle of "inverted indexing".
Column database, which stores data into the database in columns, is suitable for distributed file systems.
Graphic database uses a data structure like graph to store the relationship between entities (objects).
NoSQL.
3. Relational database design rules
3.1 Tables, records, fields
There are three main concepts in the E-R (entity-relationship) model: entity set, attribute, and contact set.
An entity set corresponds to a table in the database, and an entity (instance) corresponds to a row in the database table, also known as a record (recode). An attribute corresponds to a column in a database table, also known as a field.
ORM idea (Object Relational Mapping), object relational mapping.
3.2 Table association relationship
3.2.1 One-to-one association (one-to-one)
The records of the two tables are one-to-one correspondence, and there are not many actual development and application.
Two table building principles:
Foreign keys are unique: the primary key of the primary table and the foreign key of the slave table (unique), forming a primary and foreign key relationship, and the foreign key is unique.
Foreign keys are primary keys: the primary key of the primary table and the primary key of the slave table, forming a primary foreign key relationship.
3.2.3 One-to-many relationship
The principle of one-to-many table building: Create a field in the slave table (multiple parties), and the field is used as a foreign key to point to the primary key of the main table (one party).
3.2.3 Many-to-many
To represent a many-to-many relationship, a third table must be created, commonly known as a join table, which divides the many-to-many relationship into two one-to-many relationships, inserting both of the primary keys of the two tables into the third table.
3.3.4 Self reference