I'm wondering if there's a SQL clause for "date is not before"?
I don't want date greater than, because some of my values are blank, and I want the clause to capture those blank values.
So basically, date not before 17/03/2021 would bring back a count of "27".
date
count
16/03/2021
5
17/03/2021
4
18/03/2021
12
blank
11
Many thanks,
Nam
I would suggest using a where clause something like the following...
WHERE (Date >= '20210317' OR Date IS NULL)
Let me assume that "blank" means NULL. In Standard SQL, you need an explicit comparison for this. And you need a date constant:
where "date" >= date '2021-03-17' or "date" is null
You can also use coalesce():
where coalesce("date", '2199-12-31') >= date '2021-03-17'
but this can prevent the optimizer from choosing the best execution plan.
Related
Here is what I did:
Select count(check_id)
From Checks
Where timestamp::date > '2012-07-31'
Group by 1
Is it right to do it like I did or is there a better way? Should/could I have used the DateDIFF function in my WHERE clause? Something like: DATEDIFF(day, timestamp, '2012/07/31') > 0
Also, I need to figure out how I'd calculate the total rate of acceptance for this
time period? Can anyone provide their expertise with this?
Is it right to do it like I did or is there a better way?
Using a cast like that is a perfectly valid way to convert a timestamp to a date (I don't understand the reference to the non-existing datediff though - why would adding anything to a timestamp change it)
However, the cast has one drawback: if there is an index on the column "timestamp" it won't be used.
But as you just want a range after a certain date, there is no reason to cast the column to begin with.
The following will achieve the same thing as your query, but can make use of an index on the column "timestamp" in case there is one and using it is considered beneficial by the optimizer.
Select count(distinct check_id)
From Checks
Where "timestamp" > date '2012-07-31' + 1
Note the + 1 which selects the day after, otherwise the query would include rows that are on that date but after midnight.
I removed the unnecessary group by from your query.
If you want to get a count per day, then you will need to include the day in the SELECT list. In that case casting is a good way to do it:
Select "timestamp"::date, count(distinct check_id)
From Checks
Where "timestamp" > date '2012-07-31' + 1
group by "timestamp"::date
I am trying to query my postgresql db to return results where a date is in certain month and year. In other words I would like all the values for a month-year.
The only way i've been able to do it so far is like this:
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN '2014-02-01' AND '2014-02-28'
Problem with this is that I have to calculate the first date and last date before querying the table. Is there a simpler way to do this?
Thanks
With dates (and times) many things become simpler if you use >= start AND < end.
For example:
SELECT
user_id
FROM
user_logs
WHERE
login_date >= '2014-02-01'
AND login_date < '2014-03-01'
In this case you still need to calculate the start date of the month you need, but that should be straight forward in any number of ways.
The end date is also simplified; just add exactly one month. No messing about with 28th, 30th, 31st, etc.
This structure also has the advantage of being able to maintain use of indexes.
Many people may suggest a form such as the following, but they do not use indexes:
WHERE
DATEPART('year', login_date) = 2014
AND DATEPART('month', login_date) = 2
This involves calculating the conditions for every single row in the table (a scan) and not using index to find the range of rows that will match (a range-seek).
From PostreSQL 9.2 Range Types are supported. So you can write this like:
SELECT user_id
FROM user_logs
WHERE '[2014-02-01, 2014-03-01]'::daterange #> login_date
this should be more efficient than the string comparison
Just in case somebody land here... since 8.1 you can simply use:
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN SYMMETRIC '2014-02-01' AND '2014-02-28'
From the docs:
BETWEEN SYMMETRIC is the same as BETWEEN except there is no
requirement that the argument to the left of AND be less than or equal
to the argument on the right. If it is not, those two arguments are
automatically swapped, so that a nonempty range is always implied.
SELECT user_id
FROM user_logs
WHERE login_date BETWEEN '2014-02-01' AND '2014-03-01'
Between keyword works exceptionally for a date. it assumes the time is at 00:00:00 (i.e. midnight) for dates.
Read the documentation.
http://www.postgresql.org/docs/9.1/static/functions-datetime.html
I used a query like that:
WHERE
(
date_trunc('day',table1.date_eval) = '2015-02-09'
)
or
WHERE(date_trunc('day',table1.date_eval) >='2015-02-09'AND date_trunc('day',table1.date_eval) <'2015-02-09')
I have a fairly large table in which one of the columns is a date column. The query I execute is as follows.
select max(date) from tbl where date < to_date('10/01/2010','MM/DD/YYYY')
That is, I want to find the cell value closest to and less than a particular date value. This takes considerable time because of the max on the large table. Is there a faster way to do this? maybe using LAST_VALUE?
Put an index on the date column and the query should be plenty fast.
1) Add an index to the date column. Simply put, an index allows the database engine to store information about the data so it will speed up most queries where that column is one of the clauses. Info here http://docs.oracle.com/cd/B28359_01/server.111/b28310/indexes003.htm
2) Consider adding a second clause to the query. You have where date < to_date('10/01/2010','MM/DD/YYYY') now, why not change it to:
where date < to_date('10/01/2010','MM/DD/YYYY') and date > to_date('09/30/2010', 'MM/DD/YYYY')
since this will reduce the number of scanned rows.
Try
select date from (
select date from tbl where date < to_date('10/01/2010','MM/DD/YYYY') order by date desc
) where rownum = 1
I have a query stated:
select *
from tblClient
where IntakeDate = #5/31/2011#
I know for a fact there are 8 records that have that date. But none of records with that date are pulled by this query. Those 8 records have times as well as "short date" (e.g. "5/31/2011 1:42:00 PM")
As a test I set the date to exactly 5/31/2011 for one record, and the query will work for that one record. Clearly the time value is interfering with this query.
I do not want to change all the date data to a strict 'short date' format and would like to work with it as-is. Can anyone give me some idea how I can make this work?
Create a condition that encompasses a single day's time range:
select *
from tblClient
where IntakeDate >= #5/31/2011# AND < #6/1/2011#
[You could use the DateValue() function on your column, but that would prevent any index being used.]
The DateValue function truncates the time off the date
select *
from tblClient
where DateValue(IntakeDate) = #5/31/2011#
See the image below. I have a table, tbl_AccountTransaction in which I have 10 rows. The lower most table having columsn AccountTransactionId, AgreementId an so on. Now what i want is to get a single row, that is sum of all amount of the agreement id. Say here I have agreement id =23 but when I ran my query its giving me two rows instead of single column, since there is nano or microsecond difference in between the time of insertion.
So i need a way that will give me row 1550 | 23 | 2011-03-21
Update
I have update my query to this
SELECT Sum(Amount) as Amount,AgreementID, StatementDate
FROM tbl_AccountTranscation
Where TranscationDate is null
GROUP BY AgreementID,Convert(date,StatementDate,101)
but still getting the same error
Msg 8120, Level 16, State 1, Line 1
Column 'tbl_AccountTranscation.StatementDate' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Your group by clause is in error
group by agreementid, convert(date,statementdate,101)
This makes it group by the date (without time) of the statementdate column. Whereas the original is grouping by the statementdate (including time) then for each row of the output, applying the stripping of time information.
To be clear, you weren't supposed to change the SELECT clause
SELECT Sum(Amount) as Amount,AgreementID, Convert(date,StatementDate,101)
FROM tbl_AccountTranscation
Where TranscationDate is null
GROUP BY AgreementID,Convert(date,StatementDate,101)
Because you have a Group By StatementDate.
In your example you have 2 StatementDates:
2011-03-21 14:38:59.470
2011-03-21 14:38:59.487
Change your query in the Group by section instead of StatementDate to be:
Convert(Date, StatementDate, 101)
Have you tried to
Group by (Convert(date,...)
instead of the StatementDate
You are close. You need to combine your two approaches. This should do it:
SELECT Sum(Amount) as Amount,AgreementID, Convert(date,StatementDate,101)
FROM tbl_AccountTranscation
Where TranscationDate is null
GROUP BY AgreementID,Convert(date,StatementDate,101)
If you never need the time, the perhaps you need to change the datatype, so you don't have to do alot of unnecessary converting in most queries. SQL Server 2008 has a date datatype that doesn't include the time. In earlier versions you could add an additional date column that is automatically generated to strip out the time companent so all the dates are like the format of '2011-01-01 00:00:00:000' then you can do date comparisons directly having only had to do the conversion once. This would allow you to have both the actual datetime and just the date.
You should group by DATEPART(..., StatementDate)
Ref: http://msdn.microsoft.com/en-us/library/ms174420.aspx