MySQL time calculation function sql Date_sub () usage

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When writing SQL, you often have to pass the value time in SQL, calculate and filter the time. Before the time is calculated in the background, direct value to SQL,

Today we found that there is a more convenient SQL function that simplifies a lot of code. This function is Date_sub ().

Date_sub will subtract a time value (time interval) from a date/time value.

The usage expression in its function is: date_sub (date,interval expr type),

The parameters of type can be of types:

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

Examples of use are:

-- a year ago  select  date_sub (Curdate (), INTERVAL 1  year) as   yeartime -- a day ago  select  Date_sub (Curdate (), INTERVAL 1  day) as  Span style= "COLOR: #000000" > selecttime -- month ago  select  Date_sub (Curdate (), INTERVAL 1  MONTH) as  Span style= "COLOR: #000000" > selecttime -- three year ago  select  Date_sub (Curdate (), INTERVAL 3  year) as  Yeartime 

1. SELECT date_sub (' 2010-08-12 ', INTERVAL 3 day) as Newdate

Results: 2010-08-09

2.SELECT date_sub (' 2010-08-12 ', INTERVAL ' 3-2 ' Year_month) as Newdate

Results: 2007-06-12

3.SELECT date_sub (' 2011-09-14 2:44:36 ', INTERVAL ' 2:26 ' Hour_minute) as Newdate

Result: 2011-09-14 00:18:36

MySQL time calculation function sql Date_sub () usage