TIMESTAMP data type holds values that contain both date and time, fixed at 19 characters. The format of a
TIMESTAMP is 'YYYY-MM-DD HH:MM:SS'
In DBMSs such as MySQL,
DATETIME is a supported data type that, just like
TIMESTAMP, is used to hold date and time values, but they're not entirely the same for the following reasons:
DATETIMErequires a few more bytes for data storing than
- As specified in the MySQL documentation, MySQL converts
TIMESTAMPvalues from the current time zone to UTC for storage, and back from UTC to the current time zone for retrieval, which does not occur for other types such as
DATETIME. This is particularly convenient when working with different time zones.
- Different supported ranges: '1000-01-01 00:00:00' to '9999-12-31 23:59:59' for
DATETIME, '1970-01-01 00:00:01' UTC to '2038-01-19 03:14:07' UTC for
Retrieving data from
In order to fetch information from a
TIMESTAMP object, we can use the
extract() function, for which we specify the field from
TIMESTAMP we want. Examples of this field would be:
Let's consider the following table to work on some examples:
All payments were made in november, so let's grab these bills along with the days they were paid:
We add the AS statement to name the resulting column from using EXTRACT.
If our bills table was larger, including payments to these bills all throughout the year, we could implement extract() and an aggregate function (SUM) to show, for example, the total amount of money paid in bills by month, with a query similar to this one:
The larger our databases, the more ways available to retrieve info!
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