difference between two dates

[Andrew]

1) I have mySQL 3.23 installed. I have a record with two date/times
fields in YYYY-MM-DD HH:MM:SS format. How do I find the difference
between those two date/times? (I would also like to know it with
seconds left off.)

2) Let's say I have two records each with a date/time field in
YYYY-MM-DD HH:MM:SS format. How do I find the difference in date/times
when each field is in a different record?

Thanks,
-Andrew K

[Bill Karwin]

Andrew wrote:

1) I have mySQL 3.23 installed. I have a record with two date/times
fields in YYYY-MM-DD HH:MM:SS format. How do I find the difference
between those two date/times? (I would also like to know it with
seconds left off.)
Unfortunately, the DATEDIFF() function is only available in MySQL 4.1.1.
In my project using MySQL 3.23, I used TO_DAYS(date1) - TO_DAYS(date2).

In my case, rounding to the nearest day was appropriate. You might want
to use the TIME_TO_SEC() function to get the difference between the two
datetime values, in addition to the expression I mention above. I'll
leave the application of that function up to you.
2) Let's say I have two records each with a date/time field in
YYYY-MM-DD HH:MM:SS format. How do I find the difference in date/times
when each field is in a different record?

Join the table to itself to get values from different records into one
SQL expression.

Regards,
Bill K.