MySQL CAST() 函数
示例
将值转换为 DATE 数据类型:
SELECT CAST("2017-08-29" AS DATE);
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定义和用法
CAST() 函数将值(任何类型)转换为指定的数据类型。
提示:另请参阅转变()功能。
语法
CAST(
value AS
datatype)
参数值
Parameter |
Description |
value |
Required. The value to convert |
datatype |
Required. The datatype to convert to. Can be one of the following:
Value |
Description |
DATE |
Converts value to DATE. Format: "YYYY-MM-DD" |
DATETIME |
Converts value to DATETIME. Format: "YYYY-MM-DD HH:MM:SS" |
DECIMAL |
Converts value to DECIMAL. Use the optional M and D parameters to specify the maximum number of digits (M) and the number of digits following the decimal point (D). |
TIME |
Converts value to TIME. Format: "HH:MM:SS" |
CHAR |
Converts value to CHAR (a fixed length string) |
NCHAR |
Converts value to NCHAR (like CHAR, but produces a string with the national character set) |
SIGNED |
Converts value to SIGNED (a signed 64-bit integer) |
UNSIGNED |
Converts value to UNSIGNED (an unsigned 64-bit integer) |
BINARY |
Converts value to BINARY (a binary string) |
|
技术细节
更多示例
示例
将值转换为 CHAR 数据类型:
SELECT CAST(150 AS CHAR);
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示例
将值转换为 TIME 数据类型:
SELECT CAST("14:06:10" AS TIME);
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示例
将值转换为 SIGNED 数据类型:
SELECT CAST(5-10 AS SIGNED);
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