Averaging dates in oracle sql

Question

Is there a way to average multiple dates in oracle? avg doesn\'t do any good.

Thanks.

Answer 1

Oracle handles some date arithmetic naturally - eg TRUNC(SYSDATE) + 1 will return tomorrow's date.

So another approach is to compare your date to a constant:

1) compare distance in days to a constant (eg SYSDATE)

2) average, and then round, that calculation

3) compare the average back to SYSDATE & convert back to date.

Here's some code that does this (replace dt with whatever field has your data)

 TO_DATE(
    TRUNC(SYSDATE) - ROUND(AVG(TRUNC(SYSDATE) - TRUNC(dt)))
 )

On some sample data this ran in just under half the time of Dan A.'s approach above, and produced the same output. Only tested it against data with dates in the past, but I don't see any obvious reason that it wouldn't generalize (famous last words when dealing with DATETIME data, I realize...)