I have a mysql table that has a column that stores dates but isn't in the date format, it's a varchar.
The column is called data_hora and have dates in the dd/mm/yy format, example: 06/09/2012 15:00, so I had to convert to date format in mysql query.
And I need to get the closest date and hour before or after the current time, I came up with the following code, but for some reason it seems to get only closest date but not hour, weird?!?!
SELECT str_to_date(data_hora, '%d/%m/%Y %H:%i') AS data_hora
FROM requisicoes
ORDER BY abs(DATE_FORMAT(NOW(),'%d/%m/%Y %H:%i') - data_hora) LIMIT 1
Help :(
try this:
Your ORDER BY Clause has to be changed
SELECT str_to_date(data_hora, '%d/%m/%Y %H:%i') AS data_hora
FROM requisicoes
ORDER BY abs(TIMEDIFF( NOW() , str_to_date(data_hora, '%d/%m/%Y %H:%i'))) LIMIT 1
You shouldn't format NOW() to a string: it is already a TIMESTAMP value; instead, take the (absolute) difference between the present UNIX_TIMESTAMP() and that of the data_hora alias for your selected STR_TO_DATE() column:
ORDER BY ABS(UNIX_TIMESTAMP() - UNIX_TIMESTAMP(data_hora))
If at all possible, I would advise altering your schema so that your data_hora column is stored as a TIMESTAMP: it will greatly improve the performance of queries of this sort.
Related
I have a database, with around 500k rows, I don't know why but instead of using "Date" type on the column it uses "varchar". Now the date has a format - 01/02/2021 07:08:49 AM
My question is how should an SQL query look to delete this kind of "old" date rows from the table? Or in another hand how should I convert the column without losing the data and holding the same format to a Date type column?
I tried deleting with something like this:
DELETE FROM `visited` WHERE LEFT(`last_visit_date`, 2) != '01' OR LEFT(`last_visit_date`, 2) != '12';
However, this didn't fully clean the table.
Any help would be appreciated.
You may use STR_TO_DATE in your delete query to convert the text dates to bona fide dates:
DELETE
FROM visited
WHERE
STR_TO_DATE(last_visit_date, '%d/%m/%Y %h:%i:%s %p') < '2020-11-01';
Note that if your text dates actually have month before day, then use this call to STR_TO_DATE:
STR_TO_DATE(last_visit_date, '%m/%d/%Y %h:%i:%s %p')
If you don't want to lose the dates with the wrong format, you can update the table:
UPDATE visited
SET last_visit_date = STR_TO_DATE(last_visit_date, '%d/%c/%Y %r')
WHERE last_visit_date LIKE '__/__/____ __:__:__ __';
and change the data type of the column to DATETIME (if all the other values of last_visit_date are valid datetimes):
ALTER TABLE visited MODIFY last_visit_date DATETIME;
See a simplified demo.
I have a database where all my data have a unix timestamp as a integer, the integer is the amount of seconds since 1.jan 1970.(like what Time.now.to_i returns in ruby http://www.unixtimestamp.com).
Is there any way i can get the date from 1447277423 in SQL? I need to group the rows by date.
I want this to be done in a view, and not use another script to do it.
Is this possible?
Convert the unix timestamp to date only (since you don't want hours/seconds), then group by it.
SELECT * FROM table
GROUP BY FROM_UNIXTIME(date_timestamp, '%Y %m %d');
Or, if you don't want to actually group them and just want them outputted all in order, ORDER BY instead.
SELECT * FROM table
ORDER BY date_timestamp
/* when ordering, it doesn't matter so much if its the whole timestamp or not since the date comes first in the timestamp */
To go one further, you can SELECT the formatted date as well
SELECT *, FROM_UNIXTIME(date_timestamp, '%Y %m %d') as date_Ymd FROM table
ORDER BY date_timestamp;
FROM_UNIXTIME docs
Just use FROM_UNIXTIME():
group by DATE(FROM_UNIXTIME(your_unix_timestamp_field))
That is the nice part of unix timestamps, you can just treat it as an integer.
SELECT something FROM table WHERE date >= 1447277423
Hope this helps
I have a column that stores dates as text, I need to select all the entries with date less than the date of today.
If I use this:
SELECT *
FROM mytab
WHERE expire < CURRENT_DATE( )
ORDER BY expire DESC
It doesn't select the correct entries but only the ones with da_expire empty.
How can I fix it?
In the first place, why are you storing it as string?
You need to convert it to date using MySQL's builtin function so you can be able to compare it with today's date.
WHERE STR_TO_DATE(expire, '%Y/%m/%d %H:%i') < CURDATE()
This will be a little slower since it will not use any index if you have one defined on the column.
MySQL Docs: STR_TO_DATE()
Use STR_TO_DATE(expire, '%m/%d/%Y') instead of expire in the query. I have assumed you are storing the date in month day year format. You will need to adjust the format as per the string format. However, for performance reasons convert the type of expire during load/insert process .
SELECT * FROM table ORDER BY timestamp;
When i'm trying to order the records by its timestamp i'm getting the following order
08/20/2012 02:09:39 PM
08/20/2012 03:19:08 PM
08/20/2012 09:04:24 AM
08/20/2012 09:05:25 AM
How to change the query so that the records are ordered from AM to PM?
The problem is that your string representation of the timestamp is not in canonical format, that is, sorting the string value does not sort in timestamp order.
To get the rows sorted in order, you can convert the character representation of the value into a DATETIME or TIMESTAMP datatype, or at least into a character representation in a canonical format (e.g. 'YYYY-MM-DD hh:mm:ss' with a 24 hour clock).
The STR_TO_DATE function is useful for converting a string representation in a known format into DATETIME:
SELECT * FROM table
ORDER BY STR_TO_DATE(`timestamp`,'%m/%d/%Y %h:%i:%s %p')
http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-format
http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_str-to-date
You will want to use STR_TO_DATE()
select *
from dates
order by STR_TO_DATE(dt,'%m/%d/%Y %h:%i:%s') desc
See SQL Fiddle with demo
just add the DESC:
SELECT * FROM table ORDER BY timestamp DESC;
I try to order the results of a query by the date which is in the format yyyy/mm/dd and I am using this query to no avail.
SELECT * FROM table ORDER BY STR_TO_DATE(date, '%y/%m/%d')
I can't change the type of field that the date is stored in so I am hoping I can order the date post data entry.
Any help and advice appreciated.
If the date is in that format, you don't need to convert it to a date, surely? That format would sort alphabetically, assuming it is 0 padded... (i.e. July is 3 July 2012 is 2012/07/03...)
So you can just go:
select * from table order by date
What type of field is your date field: are you sure it is a varchar?
Assuming it is a varchar, you can work out what is going wrong by going:
select str_to_date(date, '%y/%m/%d') from table
You (should) get all NULL's, because the %y is wrong. Try:
select str_to_date(date, '%Y/%m/%d') from table
and it should work. But as noted, you don't have to convert to sort.
Try with capital Y:
SELECT * FROM table ORDER BY STR_TO_DATE(date, '%Y/%m/%d')
Lowercase Y is for yy, uppercase for yyyy.
SELECT * FROM table ORDER BY date