MySQL Database rules

Database column type

varchar string

Bit Bohr type
int integer
float decimal
Char character
DateTime date time does not fit need to turn down
Text binary/string (no length limit)

Relationship

1. Primary key

2. Self-growth column

3. Foreign key

From the table
Main Table
Master Table control from table
The foreign key column in the primary table must be a primary key

Rules:

First paradigm: Guaranteeing the atomicity of each column

Second paradigm: Ensure that each column of a data table is associated with a primary key

Third paradigm: Ensure that each column of the data table is directly related to the primary key

Splitting a table until it cannot be split

Table name prefixed with lowercase

If the primary key is not found, use the self-growing column

Foreign key relationships can be used without adding

MySQL Database rules