mysql中cast用法
语法：CAST( value AS type )
type的类型有
| value | 描述 |
|---|---|
| DATE | 日期，格式为 'YYYY-MM-DD'. |
| DATETIME | 日期加具体的时间，格式为 'YYYY-MM-DD HH:MM:SS'. |
| TIME | 时间，格式为 'HH:MM:SS'. |
| CHAR | 字符型 |
| SIGNED | int |
| UNSIGNED | 无符号int |
| BINARY | 二进制型 |
| DECIMAL | float型 |
select cast(20.3456 as decimal(10, 2)) as num
//结果：20.35
select cast('2019-03-08 15:31:26' as datetime ) as date
//结果：2019-03-08 15:31:26
select cast('2019-03-08 15:31:26' as date ) as date
//结果：2019-03-08
select cast('2019-03-08 15:31:26' as time ) as date
//结果：15:31:26
select cast('2015-11-03 15:31:26' as char ) as date
//结果：2015-11-03 15:31:26
