Diff. between dates - SQL plus [duplicate] - sql

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DateDiff Function
I am trying to find the difference between dates in SQL. The difference in days will have to be displayed when the query is given. I get an error saying that DATEDIFF is an invalid identifier. Any ideas?
Here is the table:-
Create table auctions(
item varchar2(50),
datebought date,
datesold date,
days number
);
Insert into auctions values (‘Radio’,’12-MAY-2001’,’21-MAY-2001’);
Select item,datebought,datesold,DATEDIFF(dd ,datebought,datesold )”days”
from auctions;

The title of the question includes "SQL plus", which implies Oracle to me.
Oracle does not have a DATEDIFF function. The simplest method to determine the number of days between 2 dates using Oracle is to subtract one date from the other.
Select item, datebought, datesold, datesold-datebought as days from auctions;
Oracle stores both date and time info in a date field. It is common practice to store dates truncated to midnight within date fields in Oracle if you don't care about the time.
If your dates are already truncated to midnight, then the computed value will be an integral number.
But if your stored dates include time info, then you may want to truncate the value to get an integral value. I suspect you would want to truncate each date before the subtraction, such that if bought on one day, then any time the next day would count as 1 day. Oracle truncates dates to midnight.
select item, datebought, datesold, trunc(datesold)-trunc(datebought) as days from auctions;
I agree with WarrenT that your table should not have the denormalized days column.

try this,Its working for me
Create table auctions(
item varchar(50),
datebought date,
datesold date,
days int
)
Insert into auctions(item,datebought,datesold)
values ('Radio','12-MAY-2001','21-MAY-2001')
Select item,datebought,datesold,DATEDIFF(dd ,datebought,datesold )as days
from auctions;

In a normalized database design, you would not want to define a table column whose value could be calculated from one or more other columns. You would be better off defining the days held in a SELECT or in a VIEW.
If you were using DB2, you could calculate the days held as DAYS(DATESOLD) - DAYS(DATEBOUGHT)

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