MYSQL - datetime to seconds

I wasn't able to find out (googling, reading mysql reference manual) how to get value of DATETIME in seconds in MySQL.

I dont mean to extract seconds from datetime,开发者_高级运维 but to convert it into seconds.

If by "convert to seconds", you mean "convert to an UNIX Timestamp" (i.e. number of seconds since 1970-01-01), then you can use the UNIX_TIMESTAMP function :

select UNIX_TIMESTAMP(your_datetime_field)
from your_table
where ...

And, for the sake of completness, to convert from an Unix Timestamp to a datetime, you can use the FROM_UNIXTIME function.

If you want to have the difference between two DATETIME values, use TIMESTAMPDIFF:

TIMESTAMPDIFF(unit,datetime_expr1,datetime_expr2)

Returns datetime_expr2 – datetime_expr1, where datetime_expr1 and datetime_expr2 are date or datetime expressions. One expression may be a date and the other a datetime; a date value is treated as a datetime having the time part '00:00:00' where necessary. The unit for the result (an integer) is given by the unit argument. The legal values for unit are the same as those listed in the description of the TIMESTAMPADD() function.

mysql> SELECT TIMESTAMPDIFF(MONTH,'2003-02-01','2003-05-01');  
    -> 3  



mysql> SELECT TIMESTAMPDIFF(YEAR,'2002-05-01','2001-01-01');  
    -> -1  


mysql> SELECT TIMESTAMPDIFF(MINUTE,'2003-02-01','2003-05-01 12:05:55');  
    -> 128885

unit can also be HOUR which is what you asked for in one of the comments.

The unit argument can be any of the following:

• MICROSECOND
• SECOND
• MINUTE
• HOUR
• DAY
• WEEK
• MONTH
• QUARTER
• YEAR

The level of usefulness of some of the other options will of course be determined by the granularity of the data. For instance, "MICROSECOND" will only have limited use if you are not storing microseconds in your DATETIME values.

Use TIME_TO_SEC in previous versions for mysql

SELECT TIME_TO_SEC(time column) FROM table

i used in mysql

TO_SECONDS(your date goes here) method to convert date to seconds from year 0

http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html

The function UNIX_TIMESTAMP(datetime) returns the unix time, which happens to be the number of seconds since 1-Jan-1970 0000 UTC. That may be what you need, but not if you're dealing with dates of birth, historical dates, or dates after 2037.

Starting in mysql 5.5.0 you can use to_seconds()

TO_SECONDS(FIELD_NAME)

FIELD_NAME must be DATETIME type

I have created my own query for your problem:

SELECT HOUR(`colname`) * 3600 + MINUTE(`colname`) * 60 + SECOND(`colname`)
FROM widgets
WHERE id = 1;

• Use id = 1 if you have to take a specific row.
• The output will be in seconds.