Thomas, I do not think in this case that one is better than the other, for the most part, because both require using a value computed from the column. Computing month from a DATE field should be just as fast as computing from a DATETIME column I would think.
Also splitting into DATE and TIME columns can make your SQL a bit trickier depending on your needs. That being said, one difference that might come up in extreme cases is that the size of an index on a DATE column will be smaller than on a DATETIME (fewer unique values, less cardinality) so if you have a lot of records you might be able to keep all or more of the index in memory. One potential solution might be to use an extra column that tracks month_number, and populate it with a trigger on insert or update. Index that field and then use it in your WHERE clause. One possibility anyway. HTH, Dan On 12/4/06, Thomas Bolioli <[EMAIL PROTECTED]> wrote:
If one has a large number of records per month and normally searches for things by month, yet needs to keep things time coded, does anyone know if it make sense to use datetime or separate date and a time columns? Thanks, Tom -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
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