MySQL data type selection: A guide to choosing the right data type according to your needs

MySQL data type selection guide: How to correctly select the appropriate data type according to your needs, specific code examples are required

Introduction:
When using the MySQL database, data The choice of type is very important. Choosing the right data type can not only improve the performance and storage efficiency of the database, but also ensure the accuracy and completeness of the data. This article will introduce some commonly used MySQL data types and provide specific code examples to help readers correctly choose the appropriate data type according to their own needs.

1. Integer types
MySQL provides a variety of integer types, usually selected based on data range and storage requirements.

1. TINYINT: occupies 1 byte, range is -128~127 or 0~255.

   CREATE TABLE `user` (
     `id` TINYINT UNSIGNED NOT NULL PRIMARY KEY,
     `name` VARCHAR(50) NOT NULL
   );

2. SMALLINT: Occupies 2 bytes, range is -32768~32767 or 0~65535.

   CREATE TABLE `order` (
     `order_id` SMALLINT UNSIGNED NOT NULL PRIMARY KEY,
     `total_amount` DECIMAL(8,2) NOT NULL
   );

3. MEDIUMINT: Occupies 3 bytes, range is -8388608~8388607 or 0~16777215.

   CREATE TABLE `product` (
     `product_id` MEDIUMINT UNSIGNED NOT NULL PRIMARY KEY,
     `price` DECIMAL(10,2) NOT NULL
   );

4. INT: Occupies 4 bytes, ranging from -2147483648~2147483647 or 0~4294967295.

   CREATE TABLE `customer` (
     `customer_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `name` VARCHAR(100) NOT NULL
   );

5. BIGINT: Occupies 8 bytes, ranging from -9223372036854775808~9223372036854775807 or 0~18446744073709551615.

   CREATE TABLE `transaction` (
     `transaction_id` BIGINT UNSIGNED NOT NULL PRIMARY KEY,
     `amount` DECIMAL(12,2) NOT NULL
   );

2. Floating-point type
MySQL provides a floating-point type to store values ​​with decimal points, and select the appropriate data type according to accuracy requirements.

1. FLOAT: occupies 4 bytes, and the precision is single precision. It is suitable for data with a large storage range but low precision requirements.

   CREATE TABLE `student` (
     `student_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `name` VARCHAR(100) NOT NULL,
     `score` FLOAT NOT NULL
   );

2. DOUBLE: Occupies 8 bytes, the precision is double precision, and is suitable for storing data with high precision requirements.

   CREATE TABLE `product` (
     `product_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `name` VARCHAR(100) NOT NULL,
     `price` DOUBLE NOT NULL
   );

3. String type
MySQL provides a variety of string types. Choose the appropriate data type based on storage requirements and data length.

1. CHAR: fixed-length string, which can store up to 255 characters.

   CREATE TABLE `user` (
     `user_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `username` CHAR(50) NOT NULL,
     `password` CHAR(32) NOT NULL
   );

2. VARCHAR: variable length string, can store up to 65535 characters.

   CREATE TABLE `article` (
     `article_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `title` VARCHAR(100) NOT NULL,
     `content` TEXT NOT NULL
   );

4. Date and time types
MySQL provides date and time types to store data such as date, time and timestamp.

1. DATE: Stores the date in the format YYYY-MM-DD.

   CREATE TABLE `employee` (
     `employee_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `name` VARCHAR(100) NOT NULL,
     `hire_date` DATE NOT NULL
   );

2. TIME: Storage time in the format of HH:MM:SS.

   CREATE TABLE `message` (
     `message_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `content` TEXT NOT NULL,
     `create_time` TIME NOT NULL
   );

3. DATETIME: Stores date and time in the format YYYY-MM-DD HH:MM:SS.

   CREATE TABLE `log` (
     `log_id` INT UNSIGNED NOT NULL PRIMARY KEY,
     `message` TEXT NOT NULL,
     `create_datetime` DATETIME NOT NULL
   );

Summary:
In the MySQL database, choosing the appropriate data type is very important for both storing and processing data. Through reasonable selection of integer types, floating point types, string types, and date and time types, the performance, accuracy, and storage efficiency of the database can be improved. This article provides specific code examples to help readers choose the correct data type according to their needs. Readers should make judgments and choices based on their own specific situations in practical applications to achieve the best database design and performance optimization results.

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