i'm new to MS Access..
one of my Access table CHECKOUT having a column name CHECK-TIME with Date/time data type
values in that column are like 7/15/2013 10:56:22 AM,9/19/2013 6:54:37 PM....
i want to select the data based on date like `7/15/2013'
how to write the query for this task ???
thanks in advance..
First off, the way to specify date literals is with hash (#) not any form of quote or backtick.
Secondly, you can't do LIKE comparisons with dates, not that I've ever seen anyway.
Thirdly, it's always best to specify dates in yyyy-mm-dd format because it's an unambiguous format.
This example should give you what you need:
SELECT
*
FROM
CHECKOUT
WHERE
datevalue([CHECK-TIME]) = #2013-07-15#
The datevalue() function takes a parameter, usually a string but in this case a datetime, and converts it to a date, thus stripping off the time. This allows us to check for equality against a date literal.
Related
There is this strange error in sql query.
The query is something like this.
select * from student where dob between '20150820' and '20150828'
But in the database the column of dob is varchar(14) and is in yyyyMMddhhmmss format,Say my data in the row is (20150827142545).If i fire the above query it should not retrive any rows as i have mentioned yyyyMMdd format in the query.But it retrives the row with yesterday date (i.e 20150827112535) and it cannot get the records with today's date (i.e 20150828144532)
Why is this happening??
Thanks for the help in advance
You can try like this:
select * from student
where convert(date,LEFT(dob,8)) between
convert(date'20150820') and convert(date,'20150828'))
Also as others have commented you need to store your date as Date instead of varchar to avoid such problems in future.
As already mentioned you would need to use the correct date type to have between behave properly.
select *
from student
where convert(date,LEFT(dob,8)) between '20150820' and '20150828'
Sidenote: You don't have to explicitly convert your two dates from text as this will be done implicitly as long as you use an unambiguous date representation, i.e. the ISO standard 'YYYYMMDD' or 'YYYY-MM-DD'. Of course if you're holding the values in variables then use date | datetime datatype
declare #startdate date
declare #enddate date
select *
from student
where convert(date,LEFT(dob,8)) between #startdate and #enddate
Sidenote 2: Performing the functions on your table dob column would prevent any indexes on that column from being used to their full potential in your execution plan and may result in slower execution, if you can, define the correct data type for the table dob column or use a persistent computed column or materialised view if your performance is a real issue.
Sidenote 3: If you need to maintain the time portion in your data i.e. date and time of birth, use the following to ensure all records are captured;
select *
from student
where
convert(date,LEFT(dob,8)) >= '20150820'
and convert(date,LEFT(dob,8)) < dateadd(d,1,'20150828')
All you have to do is to convert first the string to date.
select *
from student
where dob between convert(date, '20150820') and convert(date, '20150828')
Why is this happening?
The comparison is executed from left to right and the order of characters is determined by the codepage in use.
Sort Order
Sort order specifies the way that data values are sorted, affecting
the results of data comparison. The sorting of data is accomplished
through collations, and it can be optimized using indexes.
https://msdn.microsoft.com/en-us/library/ms143726.aspx
There are problems with between in T-SQL.
But if you want a fast answer convert to date first and use >= <= or even datediff to compare - maybe write a between function yourself if you want the easy use like between and no care about begin and start times ...
What do BETWEEN and the devil have in common?
I am confused with to_date(char[,'format'[,nls_lang]) function. Lets suppose I have to_date('31-DEC-1982','DD-MON-YYYY');should the format specified in the function be same as the date string? The above function works fine. When I use to_date('31-DEC-1982','DD-MM-YYYY'); also works fine but the month field in date string and that in format does not match.
So my doubt is should the date string and format specified match exactly to convert it to Date object.
Thanks
Generally speaking, yes, the date string and specified format should match. But the reason why it works in your case is that Oracle, for certain cases, provides flexibility of alternative format matching.
Excerpt from official Oracle Site
If a match fails between a datetime format element and the corresponding characters in the date string, then Oracle attempts alternative format elements
So as per above table, you can use 'MON' or 'MONTH' in place of 'MM'.
Similarly you can use 'YYYY' in place 'YY', etc
Reference:
Oracle Format Matching
Whatever format you follow, the object returned will be of date type.
You can test this via creating a dummy table and showing the table description.
e.g. CREATE TABLE TEST AS(
select to_date('31-DEC-1982','DD-MON-YYYY') dd from dual);
Now desc test;
Result will be dd date.
Similar will be the result with another type.
However if you are using SQL Developer, the date will be show in the exact NLS format as the setting there applies.
tools->preferences->database->NLS
I am querying a SQLite database table as follows:
SELECT MAX(Date) from Intra360 WHERE Date <= "05/04/2013 00:00"
The right record in return should be the number 47, i.e. 04/04/2013 23:00:
However, the execution of this statement returns a different value:
I confess I know almost nothing about SQL, but this outcome is strange. Where am I being wrong?
NOTE "Intra360" is the name of the table and the field containing the dates is called "Date"
ADDITIONAL NOTE what I need is the closest available date to a user input. It is a Python program which is making some analysis but when the user inputs the dates is not necessarily true they will exist in the database. So I'm just trying to re-select them in a way that the proper SQL statement that will load the data to be used in the analysis won't fail execution because of the missing record. So "05/04/2013 00:00" is the user input, and the query should be done hence starting from 04/04/2013 (and not definetely 04/06/2013).
The comparisons are performed on strings with alphabetical ordering, not on datetime stamps with chronological ordering.
Store your datetimes in a format that compares the way you want. For example, unix epoch timestamps and ISO 8601 yyyy-MM-dd'T'HH:mm:ss datetimes have this property.
If you cannot influence how the data is stored, you can use substr() to mangle the timestamps in SQL. See e.g. Sqlite convert string to date for more.
I have a table with two columns, all of them are datetime value
Such as, Column A with value ‘07/09/2012 14:13:34’
Now, I want to update column A to yyyymmdd by statement
Update Change_Date
SET A = CONVERT(VARCHAR(8),A,112)
It shows succsessful message but with no effect (no update value to 20120907) in my table Change_Date.
Any help will be greated, thank you!
A datetime fields saves a date time. How you see that date time is a result of the tool you're using to inspect the data, whether it is Management Studio, or your own software that's printing something from the database.
I strongly recommend keeping it as a datetime field. This will allow you to do date-related operations, such as subtractions and comparisons. If you want to change how your users see the date, then format your date at the presentation layer.
What's happening in the code you've posted is that you're setting the value of A to the same date that it already is. The fact that you're setting that value by means of a string in another format has no relation, SQL server will always have to parse your string input into a date that it can understand. This is why you're not getting an error message. The operation is working, only it's not changing anything.
You can select the date column in specified format or make a view which selects the column value in yyyymmdd format:
SELECT CONVERT(VARCHAR(8), A, 112) FROM Change_Date
It's because the datatype of the column is DATE or DATETIME and it has specific format. If you want to update the column with specific format, make another column and make its datatype VARCHAR. I believe 112 is yyyymmdd format.
I strongly suggest that you keep it AS IS. Database is the storage of data and not for viewing purposes. It is easy to perform task for dates if your data type is DATETIME or DATE. If for instance you want to retrieve the dates with specific format, that's the time you convert your date.
Hope this makes sense.
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'