convert years and weeks to date in sql msaccess - sql

how to convert text to date in sql as listed below?
Y12-W01 to 20120102
Y12-W02 to 20120109
Y12-W03 to 20120116
and so on...
i use ms-access.
thank you in advance
regards.

You don't need a separate function, try this SQL example:
SELECT FieldName, DateAdd("ww",CDbl(Mid([FieldName],6,2))-1,DateSerial(Mid([FieldName],2,2),1,1)) AS ConvDate
FROM TableName

I think the easiest method would be to make a table of dates, with one row for each week. One field would be the source format Y12-W01 and the 2nd field would be the resulting date 20120102. Join your source data to this table on the 1st field and use the 2nd field as the date in further sql or queries.

Parse your Week and Year out of your field. I'll let you figure out that one. ;o)
Once you have the Week and Year, pass them into this function:
Function GetWeekStart(weekNum As Integer, yr As Integer) As Date
GetWeekStart = DateSerial(yr, 1, 1 + (weekNum * 7) - 6 - Weekday(DateValue("1/1/" & yr)))
End Function

Related

Oracle SQL: Transpose Columns to Rows After Using Extract

I have a table with column DATE. Date is 'dd/mm/yyyy' and I want only days. So I try with extract and return what I need, but I what using transpose for column to row.
The select statement is:
select EXTRACT (DAY FROM "DATE") DAY
from people;
Is this thing possible?
Thank you!
If you have a string, then just use the leftmost two characters:
select substr("DATE", 1, 2) as day
That said, you should not be storing dates as strings. It is wrong, wrong, wrong. You cannot use the built-in date/time functions. You cannot use inequality comparisons either. Fix your data model.
The date format doesn't matter. It is linked to your NLS local settings and this is how you see this.
To have it generic and extract DAY from the date do this:
select to_char(sysdate, 'DD') from dual;
Would return 07 since it's September 7th 2020.

How I can extract year from a date in sql and use it in where clause

I have a date column in a table which is named released_date and the format of its data is for example: 01-Jan-1995. I want to have just the years which are greater than 1997. Does anybody know how I can write such query?
if the date is in dd-MMM-yyyy format, you can use regexp_extract:
select regexp_extract (released_date, '(\\d{4})$',1) as year
Try this:
SELECT * FROM table_name WHERE year(released_date) > 1997

How to compare 2 converted dates in sql

I'm trying to exclude results in my query that start in the same month between two columns. For example, I need to exclude benefits1 that start in the same month as benefits2. Format for benefit1_start_date and benefit2_start_date is: YYYYMMDD.
This is what I have so far:
where (benefit1_start_date = (to_char(sysdate, 'YYYYMM') || '0122')) <>
(benefit2_start_date = (to_char(sysdate, 'YYYYMM') || '0122'));
If anyone could put me in the right direction, I'd greatly appreciate it!
Convert your numeric dates to text, and then compare the year and month substrings:
WHERE
SUBSTR(TO_CHAR(benefits1_start_date), 1, 6) <> SUBSTR(TO_CHAR(benefits2_start_date), 1, 6)
Note that storing your dates as numbers like this is atypical, and you might want to consider storing them as dates. If you don't have a day component, you could just use the first as a placeholder.
As I understand it, you want to eliminate records where your 2 columns benefits1_start_date and benefits2_start_date are in the same month, and both have a format of YYYYMMDD.
Are they stored as strings? If so, all you need to do is compare the first 6 characters (if you need to consider yr + month), or just the 5+6th characters if you want to check just the month without the year.
Year + Month:
SUBSTR(benefits1_start_date,1,6) <> SUBSTR(benefits2_start_date,1,6)
Just month:
SUBSTR(benefits1_start_date,5,2) <> SUBSTR(benefits2_start_date,5,2)
If they're not stored as strings but as dates, then you can TRUNC the date to month and compare (for yr + month), or convert the date to MM string via to_char and compare if you just want to check the month.
Hope this helps.
I suggest you to use BETWEEN clause. Converting LEFT side operand to string by function and then making comparison can have severe performance impacts.
if you convert indexed table.dateColumn to string by to_char(table.dateColumn), oracle cannot use defined index on column anymore.
Your desired query:
where to_char(benefit1_start_date, 'YYYYMM') != to_char(benefit2_start_date, 'YYYYMM')
but
select * from table1
where months_between(benefit1_start_date, benefit2_start_date) not between -1 and 1
would be what you are looking for. (no performance impact)

How to get all rows in certain month

I have a column named DC34_DATE of type DATE (defined this way: DATE '2013-04-17'). I need to select all rows for a specific month (for example April). I have used WHERE MONTH(DC34_DATE)=04; but it doesn't work.
You can use the extract from date function to get the date. Try this.
WHERE EXTRACT(month from DC34_DATE) = '4';
select yourColumns
from yourTable
where datepart(month,yourDateColumn)=4
TSQL solution..don't know which dialect you're using.

SQL query to convert Date to another format

Thanks for your help. I am not able to make out the type/format of the "Value" in a Date column.I guess its in Julian Date format.
The Column is paid_month and the values are below.
200901
200902
So,please help in writing SQL query to convert the above values(Mostly in Julian Format) in the Date Column to normal date (MM/DD/YYYY) .
Thanks
Rohit
Hi,
I am sorry for missing in giving the whole information.
1)Its a Oracle Database.
2)The column given is Paid_Month with values 200901,200902
3)I am also confused that the above value gives month & year.Day isnt given if my guess is right.
4)If its not in Julian format ,then also please help me the SQL to get at least mm/yyyy
I am using a Oracle DB and running the query
THANKS i GOT THE ANSWER.
**Now,i have to do the reverse meaning converting a date 01/09/2010 to a String which has 6 digits.
Pls help with syntax-
select to_char(01/01/2010,**
It looks like YYYYMM - depending on your database variant, try STR_TO_DATE(paid_month, 'YYYYMM'), then format that.
Note: MM/DD/YYYY is not "normal" format - only Americans use it. The rest of the world uses DD/MM/YYYY
For MySQL check
http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-format
Example:
SELECT DATE_FORMAT(NOW(), '%d/%m/%Y')
For MySQL, you would use the STR_TO_DATE function, see http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html#function_str-to-date
SELECT STR_TO_DATE(paid_month,'%Y%m');
Sounds like the column contains some normal dates and some YYYYMM dates. If the goal is to update the entire column, you can attempt to isolate the YYYYMM dates and update only those. Something like:
UPDATE YourTable
SET paid_month = DATE_FORMAT(STR_TO_DATE(paid_month, '%Y%m'), '%m/%d/%Y')
WHERE LENGTH(paid_month) = 6
SELECT (paid_month % 100) + "/01/" + (paid_month/100) AS paid_day
FROM tbl;
I'm not sure about how oracle concatenates strings. Often, you see || in SQL:
SELECT foo || bar FROM ...
or functions:
SELECT cat (foo, bar) FROM ...