Deep understanding of MySQL data types: Explore the details and limitations of basic data types

MySQL is a powerful relational database management system (RDBMS) that is widely used in various types of applications. In MySQL, data type is one of the very important concepts. Different data types have different characteristics and limitations when storing and processing data. This article will take an in-depth look at the various basic data types in MySQL, including their details and limitations, and provide specific code examples.

1. Integer type

1. TINYINT:
   The TINYINT type is a very small integer type that can store values ​​from -128 to 127 or 0 to 255. It only takes up 1 byte in storage.

Sample code:
CREATE TABLE my_table (
id TINYINT
);

2. SMALLINT:
   The SMALLINT type can store smaller ranges An integer value from -32768 to 32767 or 0 to 65535. It takes up 2 bytes on storage.

Sample code:
CREATE TABLE my_table (
id SMALLINT
);

3. INT:
   INT type can store larger ranges integer value, from -2147483648 to 2147483647 or 0 to 4294967295. It takes 4 bytes on storage.

Sample code:
CREATE TABLE my_table (
id INT
);

4. BIGINT:
   The BIGINT type can store very large ranges The integer value ranges from -9223372036854775808 to 9223372036854775807 or 0 to 18446744073709551615. It takes up 8 bytes on storage.

Sample code:
CREATE TABLE my_table (
id BIGINT
);

2. Floating point type

1. FLOAT :
   The FLOAT type is used to store single-precision floating point numbers and can store up to 7 significant digits. It takes 4 bytes on storage.

Sample code:
CREATE TABLE my_table (
value FLOAT
);

2. DOUBLE:
   DOUBLE type is used to store double precision Floating point numbers can store up to 15 significant digits. It takes up 8 bytes on storage.

Sample code:
CREATE TABLE my_table (
value DOUBLE
);

3. String type

1. CHAR :
   CHAR type is used to store fixed-length strings, which can store up to 255 characters. It allocates all the space, so the storage space it occupies is fixed.

Sample code:
CREATE TABLE my_table (
name CHAR(10)
);

2. VARCHAR:
   VARCHAR type is used Stores variable-length strings of up to 65535 characters. It will only take up as much space as is actually stored.

Sample code:
CREATE TABLE my_table (
name VARCHAR(50)
);

4. Date and time types

1. DATE:
   The DATE type is used to store dates in the format of 'YYYY-MM-DD'.

Sample code:
CREATE TABLE my_table (
birth_date DATE
);

2. TIME:
   TIME type is used to store time, The format is 'HH:MM:SS'.

Sample code:
CREATE TABLE my_table (
start_time TIME
);

3. DATETIME:
   DATETIME type is used to store date and Time, the format is 'YYYY-MM-DD HH:MM:SS'.

Sample code:
CREATE TABLE my_table (
created_datetime DATETIME
);

5. Other common types

1. ENUM :
   ENUM type is used to store enumeration values. It can store a value from an enumerated list.

Sample code:
CREATE TABLE my_table (
status ENUM('active', 'inactive', 'deleted')
);

2. BOOLEAN:
   The BOOLEAN type is used to store Boolean values. It can only store data with value 0 or 1.

Sample code:
CREATE TABLE my_table (
is_active BOOLEAN
);

In summary, this article provides an in-depth analysis of various basic functions in MySQL. Data types and their details and limitations, with specific code examples provided. In practical applications, it is very important to choose the appropriate data type, which will directly affect the performance of the database and the correctness of the data. Through in-depth understanding and reasonable use of MySQL's data types, we can better utilize the functions and advantages of the database.

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