We are using the Oracle TRUNC() sql function to truncate dates. The column has type DATE.
What is a good and future proof option for truncating dates? Chances are that we are going to migrate to Postgress or MySql.
Example query:
SELECT *
FROM KIB_IND_SNAPSHOT
WHERE snsh_id IN (SELECT MAX(snsh_id)
FROM KIB_IND_SNAPSHOT
WHERE SNSH_STATUS = 'SUCCES'
GROUP BY TRUNC(SNSH_TIJDST_ONTST)
)
ORDER BY SNSH_TIJDST_ONTST;
Follow Universal date format i.e. YYYY-MM-DD which will future proof it(as of now :) ).Please refer following URL https://www.w3.org/TR/NOTE-datetime for details.
Update : BTW the answer I gave is for scenario where you want to migrate your DB to other Database. Following this will give you less headache
Related
I'm trying to find the number of days between two date columns.
I tried to use DATEDIFF but I got an error. What more should I do
Thanks,
Are you sure you are using the correct SQL syntax for your database? Since you're using MySQL, you need to do a
SELECT DATEDIFF('2015-06-05', '2015-08-05');
and the difference is always expressed in days.
On SQL Server you need to specify the unit e.g.
SELECT DATEDIFF(day, '2015-06-05', '2015-08-05');
I am importing records from a DB2 data source into a MS SQL Server destination.
The records are coming in with the date format of 20150302/YYYYMMDD, but I only want the last 14 days based on current server date.
Can some advise on how to select based on this date format against DATEADD(d, - 1, { fn CURDATE() }) please.
Thanks!
It would be better to do this on the DB2 side, to reduce the number of records brought over.
Additionally, it's better from a performance standpoint to convert the static date into a numeric date and compare to the column in your table. Rather than convert the numeric date in your table to a actual date type for comparison.
where numdate >= int(replace(char(current_date - 14 days,iso),'-',''))
Doing it this way will allow you to take advantage of an index over numdate. In addition, DB2 will only need to perform this conversion once.
Depending on your platform & version, you may have an easier way to convert from a date data type to a numeric date. But the above works on DB2 for i and should work on most (all?) DB2 versions and platforms.
You may find it worthwhile to create a UDF to do this conversion for you.
If you want logic in SQL Server, then you are in luck, because you can just convert the YYYYMMDD format to a date:
where cast(datecol as date) >= cast(getdate() - 14 as date)
(This assumes no future dates.)
If you want to do this on the DB2 side, you can use to_date():
where to_date(datecol, 'YYYYMMDD') >= current date - 14 days
I need a way to substract to dates and get the result in days in sql.
I'm using PostgreSQL 8.4
When both columns you want to subtract are of date type, you can just use the - operator.
Take a look at the documentation for date functions, in particular table 9-25.
Check here the documentation of PostgreSQl...
postgresql.org/docs/8.4
I copied it from this code from this website:
age(timestamp '2001-04-10', timestamp '1957-06-13')
hope it will help you...
I have a query in which I want to select data from a column where the data is a date. The problem is that the data is a mix of text and dates.
This bit of SQL only returns the longest text field:
SELECT MAX(field_value)
Where the date does occur, it is always in the format xx/xx/xxxx
I'm trying to select the most recent date.
I'm using MS SQL.
Can anyone help?
Try this using ISDATE and CONVERT:
SELECT MAX(CONVERT(DateTime, MaybeDate))
FROM (
SELECT MaybeDate
FROM MyTable
WHERE ISDATE(MaybeDate) = 1) T
You could also use MAX(CAST(MaybeDate AS DateTime)). I got in the (maybe bad?) habit of using CONVERT years ago and have stuck with it.
To do this without a conversion error:
select max(case when isdate(col) = 1 then cast(col as date) end) -- or use convert()
from . . .
The SQL statement does not specify the order of operations. So, even including a where clause in a subquery will not guarantee that only dates get converted. In fact, the SQL Server optimizer is "smart" enough to do the conversion when the data is brought in and then do the filtering afterwards.
The only operation that guarantees sequencing of operations is the case statement, and there are even exceptions to that.
Another solution would be using PATINDEX in WHERE clause.
SELECT PATINDEX('[0-9][0-9]/[0-9][0-9]/[0-9][0-9][0-9][0-9]', field_value)
Problem with this approach is you really are not sure if something is date (e.g. 99/99/9999 is not date).
And problem with IS_DATE is it depends on configuration (e.g. DATEFORMAT).
So, use an appropriate option.
I have a value in field called "postingdate" as string in 2009-11-25, 12:42AM IST format, in a table named "Post".
I need the query to fetch the details based on date range. I tried the following query, but it throws an error. Please guide me to fix this issue. Thanks in advance.
select postingdate
from post
where TO_DATE(postingDate,'YYYY-MM-DD')>61689
and TO_DATE(postingDate,'YYYY-MM-DD')<61691
As you've now seen, trying to perform any sort of query against a string column which represents a date is a problem. You've got a few options:
Convert the postingdate column to some sort of DATE or TIMESTAMP datatype. I think this is your best choice as it will make querying the table using this field faster, more flexible, and less error prone.
Leave postingdate as a string and use functions to convert it back to a date when doing comparisons. This will be a performance problem as most queries will turn into full table scans unless your database supports function-based indexes.
Leave postingdate as a string and compare it against other strings. Not a good choice as it's tough to come up with a way to do ranged queries this way, as I think you've found.
If it was me I'd convert the data. Good luck.
In SQL Server you can say
Select postingdate from post
where postingdate between '6/16/1969' and '6/16/1991'
If it's really a string, you're lucky that it's in YYYY-MM-DD format. You can sort and compare that format as a string, because the most significant numbers are on the left side. For example:
select *
from Posts
where StringDateCol between '2010-01-01' and '2010-01-02'
There's no need to convert the string to a date, comparing in this way is not affected by the , 12:42AM IST appendage. Unless, of course, your table contains dates from a different time zone :)
You will need to convert your string into a date before you run date range queries on it. You may get away with just using the string if your not interested in the time portion.
The actual functions will depend on your RDBMS
for strings only
select * from posts
where LEFT(postingDate,10) > '2010-01-21'
or
for datetime ( Sybase example)
select * from posts
where convert(DateTime,postingDate) between '2010-01-21' and '2010-01-31'