How to rewrite simple SQL condition for better performance

Question

I have a simple query below to select available assets from a table based on their checkout and expected return date. If the checkout and expected return date overlaps with the @RentStartDate and @RentEndDate then I want to select it as UnavailableAsset . Please see my query below

set @RentStartDate = '2016-10-13';
set @RentEndDate = '2016-10-18';

SELECT AssetID as UnAvailableAsset
FROM agreementasset
WHERE (CheckOutDate >= @RentStartDate AND CheckOutDate <= @RentEndDate)
OR
(ExpectedReturnDate >= @RentStartDate AND ExpectedReturnDate <= @RentEndDate)
OR
(@RentStartDate >= CheckOutDate AND @RentEndDate <= ExpectedReturnDate);

Now i know that this query works perfectly, but I'm just not sure if there is a better way to write the conditions in the where clause. Is there a better way to simplify the conditions to make this query more efficient?

Thanks

Answer 1

Based on the description of what you are doing, I don't understand why you think your query works.

The overlap query should look like this:

SELECT AssetID as UnAvailableAsset
FROM agreementasset
WHERE CheckOutDate <= @RentEndDate AND
      ExpectedReturnDate >= @RentStartDate;

This type of query can be difficult to optimize (in most databases). You can start with an index on agreementasset(CheckOutDate, ExpectedReturnDate, AssetID) .

Answer 2

Have you tried using the BETWEEN keyword?

SELECT AssetID as UnAvailableAsset
FROM agreementasset
WHERE (CheckOutDate BETWEEN @RentStartDate AND @RentEndDate)
OR (ExpectedReturnDate BETWEEN @RentStartDate AND @RentEndDate)

Answer 3

I don't think you can streamline and no duplicate conditions

SELECT AssetID as UnAvailableAsset
FROM agreementasset
WHERE (@RentStartDate <= CheckOutDate       AND @RentEndDate >= CheckOutDate)
   OR (@RentStartDate >= CheckOutDate       AND @RentEndDate <= ExpectedReturnDate)
   OR (@RentStartDate <= ExpectedReturnDate AND @RentEndDate >= ExpectedReturnDate);