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MySQL DATE_ADD()函数
其实我一直觉得叫DATE_ADD()函数不合理，老误导别人，因为不仅仅是日期的增加，其实我很多时候是用他来减法的。是不是改成DATE_CHANGE()更好？：）
定义和用法
DATE_ADD() 函数向日期添加指定的时间间隔。
用法：
[sql]
DATE_ADD(date,INTERVAL expr type)
date 参数是合法的日期表达式。expr 参数是您希望添加的时间间隔。 type表示类型。
type 参数可以是下列值：
Type 值
MICROSECOND
SECOND
MINUTE
HOUR
DAY
WEEK
MONTH
QUARTER
YEAR
SECOND_MICROSECOND
MINUTE_MICROSECOND
MINUTE_SECOND
HOUR_MICROSECOND
HOUR_SECOND
HOUR_MINUTE
DAY_MICROSECOND
DAY_SECOND
DAY_MINUTE
DAY_HOUR
YEAR_MONTH
如：
[sql]
DATE_ADD(#BIZ_DATE#,INTERVAL -1 DAY)
这里表示#BIZ_DATE#减去一天
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