[Mysql] CONVERT function

CONVERT function is used to convert a value to the specified data type or character set

1. Convert the specified character set

The CONVERT function is used to convert the character set of the string expr into transcoding_name

Syntax structure

CONVERT(expr USING transcoding_name)

expr: value to convert

transcoding_name: character set to convert to

-- utf8mb4SELECT CHARSET('ABC');--gbkSELECT CHARSET(CONVERT('ABC' USING gbk));

2. Convert the specified data type

The CONVERT function is used to convert the character set of the string expr into transcoding_name

Syntax structure

CONVERT(expr,type)

expr: value to convert

type: The data type to convert to

value of the type parameter

value

Description

DATE

Convert expr to 'YYYY-MM-DD' format

DATETIME

Convert expr to 'YYYY-MM-DD HH:MM:SS' format

TIME

Convert expr to 'HH:MM:SS' format

CHAR

Convert expr to CHAR (fixed-length string) format

SIGNED

Convert expr to INT (signed integer) format

UNSIGNED

Convert expr to INT (unsigned integer) format

DECIMAL

Convert expr to FLOAT (floating point) format

BINARY

Convert expr to binary format

Example

1. Convert the value to DATE data type

-- 2022-05-25SELECT CONVERT('2022-05-25', DATE);-- 2022-05-25 17:58:48SELECT NOW();-- 2022-05-25SELECT CONVERT(NOW(), DATE);

2. Convert the value to DATETIME data type

-- 2022-05-25 00:00:00SELECT CONVERT('2022-05-25', DATETIME);

3. Convert the value to the TIME data type

-- 14:06:10SELECT CONVERT('14:06:10', TIME);-- 2022-05-25 17:25:12SELECT NOW();-- 17:25:12SELECT CONVERT(NOW(), TIME);

4. Convert the value to CHAR data type

-- '150'SELECT CONVERT(150, CHAR);-- errorSELECT CONCAT('Hello World',437));-- 'Hello World437'SELECT CONCAT('Hello World',CONVERT(437, CHAR));

5. Convert the value to the SIGNED data type

-- 5SELECT CONVERT('5.0', SIGNED);-- 2SELECT (1 + CONVERT('3', SIGNED))/2;-- -5SELECT CONVERT(5-10, SIGNED);-- 6SELECT CONVERT(6.4, SIGNED);-- -6SELECT CONVERT(-6.4, SIGNED);-- 7SELECT CONVERT(6.5, SIGNED);-- -7SELECT CONVERT(-6.5, SIGNED);

6. Convert the value to UNSIGNED data type

-- 5SELECT CONVERT('5.0', UNSIGNED);-- 6SELECT CONVERT(6.4, UNSIGNED);-- 0SELECT CONVERT(-6.4, UNSIGNED);-- 7SELECT CONVERT(6.5, UNSIGNED);-- 0SELECT CONVERT(-6.5, UNSIGNED);

7. Convert the value to DECIMAL data type

-- 9SELECT CONVERT('9.0', DECIMAL);-- DECIMAL (numeric precision, decimal point retention length)-- DECIMAL(10,2) can store numbers with up to 8 integers and 2 decimals-- Precision and scale are 10 and 2, respectively-- Precision is the total number of digits, including the sum of digits to the left and right of the decimal point-- The number of decimal places is the number of digits to the right of the decimal point-- 9.50SELECT CONVERT('9.5', DECIMAL(10,2));-- 99999999.99SELECT CONVERT('1234567890.123', DECIMAL(10,2));-- 220.232SELECT CONVERT('220.23211231', DECIMAL(10,3));-- 220.232SELECT CONVERT(220.23211231, DECIMAL(10,3));

CAST function can also realize data type conversion

Supplementary Information | CAST Function

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