Introduction to data types in MySQL and their application scenarios

MySQL is a common relational database management system that is widely used in various systems and applications. In MySQL, data is stored in tables in different data types. This article will introduce common data types and their application scenarios in MySQL, with code examples.

1. Integer type

1. Integer type (INT): used to store positive and negative integer values. Different subtypes can be selected according to the number of stored digits, such as TINYINT, SMALLINT, MEDIUMINT and BIGINT. Suitable for storing large numbers of integers, such as the user's age, student ID number, etc.

Sample code:

CREATE TABLE students (
  id INT PRIMARY KEY,
  name VARCHAR(50),
  age TINYINT
);

2. Unsigned integer type (UINT): Similar to the integer type, but can only store non-negative integer values. Suitable for storing non-negative integers, such as the number of items, ratings, etc.

Sample code:

CREATE TABLE products (
  id INT PRIMARY KEY,
  name VARCHAR(50),
  quantity INT UNSIGNED
);

2. Floating point type

1. Floating point type (FLOAT): used to store single-precision floating point values, occupying 4 bytes of storage space. Suitable for storing floating point numbers that do not require very high precision, such as product prices, temperatures, etc.

Sample code:

CREATE TABLE products (
  id INT PRIMARY KEY,
  name VARCHAR(50),
  price FLOAT
);

2. Double-precision floating-point type (DOUBLE): used to store double-precision floating-point values, occupying 8 bytes of storage space. Suitable for floating point numbers that require higher precision, such as scientific computing, financial fields, etc.

Sample code:

CREATE TABLE measurements (
  id INT PRIMARY KEY,
  date DATE,
  temperature DOUBLE
);

3. String type

1. String type (CHAR): used to store fixed-length strings, maximum Length is 255 characters. Suitable for storing fixed-length strings, such as countries, regions, etc.

Sample code:

CREATE TABLE countries (
  id INT PRIMARY KEY,
  name CHAR(50),
  population INT
);

2. Variable length string type (VARCHAR): used to store variable-length strings, with a maximum length of 65535 characters. Suitable for storing strings of uncertain length, such as user's name, address, etc.

Sample code:

CREATE TABLE customers (
  id INT PRIMARY KEY,
  name VARCHAR(100),
  address VARCHAR(200)
);

4. Date and time types

1. Date type (DATE): used to store dates of year, month and day Value, in the format YYYY-MM-DD. Suitable for storing date information, such as the user's birthday, the creation date of the order, etc.

Sample code:

CREATE TABLE users (
  id INT PRIMARY KEY,
  name VARCHAR(50),
  birthday DATE
);

2. Time type (TIME): used to store time values ​​of hours, minutes, and seconds in the format of HH:MM:SS. Suitable for storing time information, such as user login time, task execution time, etc.

Sample code:

CREATE TABLE tasks (
  id INT PRIMARY KEY,
  name VARCHAR(50),
  due_time TIME
);

The above is an introduction and code examples of common data types and their application scenarios in MySQL. By rationally selecting and using data types, various types of data can be better stored and processed, and the performance and stability of the system can be improved.

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