Adjust prices in dates

I have a main pricelist which is defined something like

periodstart periodend   price
2011/01/01  2011/05/30  50
2011/06/01  2011/08/31  100
2011/09/01  2011/12/31  50

Now I would like to add the possibility of adjusting prices just for certain dates, 2011/06/15 - 98, 2011/06/16 - 98, 2011/06/23 - 95 etc. Fo开发者_开发技巧r that I planned a new table in order to keep the original pricelist unmodified.

Now I have a doubt should it be more easier to store single dates, or also work with periods

periodstart periodend   price
2011/06/15 - 2011/06/16 98
2011/06/23 - 2011/06/23 95

or

date       price
2011/06/15 98
2011/06/16 98
2011/06/23 95

It would be easier to store and later adjust prices for single dates solution, but on the other hand it would take much more rows to store price change for a continuous range of dates.

I would like to hear different views and ideas for this solution.

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the dual date option allows you to have gaps in coverage - and overlaps.

neither are what you want in a single timeline of prices. you could enforce continuity with some business logic, but that is cumbersome.

the single date option is automatically interpreted as a single timeline - but you have slightly more effort to determine bounding dates because you need to look at two records, not one.

this is an easy trade off to me - go with the single date.

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Hard to say which is better for you without knowing the distribution of data, but even in the case where you go one record per day, it's still a pretty inconsequential number of records. I mean, in 10 years you'll have 3650 rows. Big deal.