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Datetime & Timestamp manipulation / migration explained

Jun 15, 2010

Are you doing some datetime manipulation or maybe you are migrating from some database technology to MySQL or possibly using milliseconds?
Here is an example on how to go about it:
Say you have the following date: MAR 16 2008 09:12:51:893AM
SELECT DATE_FORMAT(STR_TO_DATE(‘MAR 16 2008 09:12:51:893AM’,'%M %d %Y %h:%i:%s:%f%p’),’%Y%m%d%k%i%s.%f’); –> 2008031691251.893000

What if its PM rather than AM
SELECT DATE_FORMAT(STR_TO_DATE(‘MAR 16 2008 09:12:51:893PM’,'%M %d %Y %h:%i:%s:%f%p’),’%Y%m%d%k%i%s.%f’); –> 20080316211251.893000

Ok so this is just simple string manipulation where:
%M is the month name
%d is day number
%Y is the year
%h is the hour
%i is the minute
%s is the second
%f is the microsecond
%p is the period: ante or post meridiem
In the DATE_FORMAT part we se a %k which is in 24hr format in order to loose the period.
A more detailed list is found here
Here is a demo:
mysql Tue Jun 15 12:32:37 2010 > CREATE TABLE test.abc(a DECIMAL(17,3)) ENGINE=MYISAM;
Query OK, 0 rows affected (0.03 sec)
mysql Tue Jun 15 12:32:45 2010 > INSERT INTO abc VALUES ( DATE_FORMAT(STR_TO_DATE(‘MAR 16 2008 09:12:51:893PM’,'%M %d %Y %h:%i:%s:%f%p’),’%Y%m%d%k%i%s.%f’) );
Query OK, 1 row affected (0.01 sec)
mysql Tue Jun 15 12:32:51 2010 > SELECT * FROM abc;
+——————–+
| a ? ? ? ? ? ? ? ? ?|
+——————–+
| 20080316211251.893 |
+——————–+
1 row in set (0.00 sec)

mysql Tue Jun 15 12:32:56 2010 > SELECT TIMESTAMP(a) FROM abc;
+—————————-+
| TIMESTAMP(a) ? ? ? ? ? ? ? |
+—————————-+
| 2008-03-16 21:12:51.893000 |
+—————————-+
1 row in set (0.00 sec)

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