How to get available dates with reservations?

I开发者_开发百科 am trying to build a system which lets users reserve a item, let's say a laptop..

My table looks like this:

Table 'items'
id int(20) PK auto_increment
type int(20) FK(types.id)
name varchar(200)

Table 'types'
id int(20) PK auto_increment
name varchar(200)

Table 'reservations'
id int(20) PK auto_increment
user int(20) FK(users.id)
startDate datetime
endDate datetime

Lets say I have 1 type (laptops) and 3 laptops all with the same specs, and a user just wants to reserve one laptop. How would I get all available dates for just a laptop ?

I dont mind how this is reached, either via PHP or MySQL, I just intend on letting users have a list with available dates for the given type of item..

If your reservation form prompts for $start and $end date/times for the reservation, this query will tell which laptops are available throughout the period specified by those two dates:

SELECT items.id, items.name
FROM items
LEFT JOIN types ON items.type = types.id
LEFT JOIN reservations ON reservations.item_id = items.id
WHERE (((reservations.endDate NOT between $start AND $end) and
      (reservations.startDate NOT between $start AND $end)) or
      (reservations.id IS NULL)) and
      (types.id = $laptop_type_id)

The first two between clauses will find any laptops whose start/end dates do not fall withing the requested start/end dates - e.g. they're reserved, but are available in the specified time range. The null check will find any laptops that not reserved at all. And the types.id check restricts the search to only laptops.