How can I find the difference between two dates in MySQL?
DATEDIFF returns the difference in days between two dates:
http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_datediff
mysql> select current_date()>'2011-01-01 12:01:01';
+--------------------------------------+
| current_date()>'2011-01-01 12:01:01' |
+--------------------------------------+
| 1 |
+--------------------------------------+
1 row in set (0.00 sec)
mysql> select '2011-01-01 12:01:01' > current_date();
+----------------------------------------+
| '2011-01-01 12:01:01' > current_date() |
+----------------------------------------+
| 0 |
+----------------------------------------+
1 row in set (0.00 sec)
mysql>
learn DATEDIFF
eg : SELECT DATEDIFF('2007-12-31 23:59:59','2007-12-30');
Related
mysql> select timestamp('2017-06-21 23:45:01') - timestamp('2017-06-21 23:44:58');
+---------------------------------------------------------------------+
| timestamp('2017-06-21 23:45:01') - timestamp('2017-06-21 23:44:58') |
+---------------------------------------------------------------------+
| 43 |
+---------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> select version();
+------------+
| version() |
+------------+
| 5.7.16-log |
+------------+
1 row in set (0.00 sec)
Obviously, it is not calculated as timestamp. Please advise.
You have to use TIMEDIFF() or TIMESTAMPDIFF()
DEMO
SELECT TIMEDIFF(timestamp('2017-06-21 23:45:00') , timestamp('2017-06-21 23:44:58'));
-- result: 00:00:02.
SELECT TIMESTAMPDIFF(SECOND,'2017-06-21 23:45:00','2017-06-21 23:44:58');
-- result: -2
Simple MAX query:
SELECT MAX(Group) FROM acme
Works fine on a numeric column.
Is it possible to use to this on an alpha-numeric column and ignore anything other than a number?
yes if you cast it before use like this
mysql> SELECT MAX(CAST("123" AS UNSIGNED));
+------------------------------+
| MAX(CAST("123" AS UNSIGNED)) |
+------------------------------+
| 123 |
+------------------------------+
1 row in set (0.00 sec)
mysql> SELECT MAX(CAST("abc" AS UNSIGNED));
+------------------------------+
| MAX(CAST("abc" AS UNSIGNED)) |
+------------------------------+
| 0 |
+------------------------------+
1 row in set, 1 warning (0.00 sec)
mysql> SELECT MAX(CAST("-123" AS SIGNED));
+-----------------------------+
| MAX(CAST("-123" AS SIGNED)) |
+-----------------------------+
| -123 |
+-----------------------------+
1 row in set (0.00 sec)
replace your string column name with "abc" and modify query acording to your requirment
This is my table:
+----------+---------------------+
| estimate | timestamp |
+----------+---------------------+
| 05:00:00 | 2015-12-02 13:35:14 |
+----------+---------------------+
1 row in set (0.00 sec)
I am trying to implement a scheduled job to create extra automatic rows every hour to substract the time that has past from the estimated time.
I am able to start the scheduled job and use timediff to calculate the time that has passed since, but i am unable to substract the timediff from the estimated time.
I am guessing that mysql doesn't care much that i want the estimated time column to be stated as a period of time. instead, it just shows me a time without the date.
select timediff(now(),timestamp) from t1;
this gives me the time difference that i need:
+---------------------------+
| timediff(now(),timestamp) |
+---------------------------+
| 00:27:03 |
+---------------------------+
1 row in set (0.00 sec)
but when i do this:
select estimate-timediff(now(),timestamp) as timeleft from t1;
the result is:
+----------+
| timeleft |
+----------+
| 46568 |
+----------+
1 row in set (0.01 sec)
what i would like to get:
+----------+
| timeleft |
+----------+
| 04:32:57 |
+----------+
1 row in set (0.01 sec)
The times may be a little off in my example obviously because of the timediff() but hopefully you understand my issue. There must be an easy solution that i'm missing but i've spent half a day googleing to get to this point but timediff just won't cut me some slack.
Please and thank you!
PS. I haven't found the solution yet but i think i found what might cause the problem. Obvioysly the substraction is done by using absolute values 'estimate' column doesn't use seconds as it's absolute value and the result is completely wrong.
mysql> select abs(estimate) from t1;
+----------+
| abs(estimate) |
+----------+
| 50000 |
+----------+
1 row in set (0.00 sec)
and
mysql> select abs(timediff(now(),timestamp)) from t1;
+--------------------------------+
| abs(timediff(now(),timestamp)) |
+--------------------------------+
| 2318 |
+--------------------------------+
1 row in set (0.00 sec)
So is there an easy way to force mysql to use seconds on a time column? or is something wrong with my table and the estimate format is wrong?
use timediff like that :-
timediff(estimate,timediff(now(),timestamp))
your query :-
select timediff(estimate,timediff(now(),timestamp))
as timeleft from t1;
Is it possible to configure MySQL to return TIMESTAMP value as a UNIXTIMESTAMP by default, rather than casting every column in the SELECT statement?
MySQL has a function to convert a date to a unix timestamp.
https://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html#function_unix-timestamp
mysql> SELECT UNIX_TIMESTAMP();
-> 1196440210
mysql> SELECT UNIX_TIMESTAMP('2007-11-30 10:30:19');
-> 1196440219
You cannot do that in MySQL configuration.
You can do that on application level - e.g. in PHP, you can use the mysqli_result::fetch_fields() method to detect timestamp type and convert it, other connectors will have similar methods.
Or you can do it - as suggested - using UNIX_TIMESTAMP() function on timestamp columns.
It sounds as though you want a different view of the same data:
mysql> select * from t;
+------+---------------------+
| data | ts |
+------+---------------------+
| foo | 2013-03-19 16:54:45 |
+------+---------------------+
1 row in set (0.00 sec)
mysql> select data, unix_timestamp(ts) from t;
+------+--------------------+
| data | unix_timestamp(ts) |
+------+--------------------+
| foo | 1363712085 |
+------+--------------------+
1 row in set (0.00 sec)
mysql> create view tv (data, time_t) as select data, unix_timestamp(ts) from t;
Query OK, 0 rows affected (0.00 sec)
mysql> select * from tv;
+------+------------+
| data | time_t |
+------+------------+
| foo | 1363712085 |
+------+------------+
1 row in set (0.00 sec)
I'm, trying to calculate the number of days between two dates using ANSI SQL standard. But I'm missing something as this statement returns NULL in MySQL.
SELECT EXTRACT(DAY FROM DATE('2009-01-25') - DATE('2009-01-01')) AS day_diff;
I'm aware of the MySQL DATEDIFF function, but I'm curious why this code isn't working.
What am I missing?
Is this what you meant to do?
mysql> SELECT EXTRACT(DAY FROM DATE('2009-01-25')) -
EXTRACT(DAY FROM DATE('2009-01-01')) AS day_diff;
+----------+
| day_diff |
+----------+
| 24 |
+----------+
1 row in set (0.00 sec)
UPDATE:
If you want this to work for dates in different months (or even different years), then you can use the MySQL DATEDIFF() function.
Examples:
mysql> select datediff('2009-04-25','2009-01-01');
+-------------------------------------+
| datediff('2009-04-25','2009-01-01') |
+-------------------------------------+
| 114 |
+-------------------------------------+
1 row in set (0.00 sec)
mysql> select datediff('2010-04-25','2009-01-01');
+-------------------------------------+
| datediff('2010-04-25','2009-01-01') |
+-------------------------------------+
| 479 |
+-------------------------------------+
1 row in set (0.00 sec)