Add two IQueryables (int/decimal) in C#

I am pulling two values from a MYSQL database. I have one int and one deci开发者_JAVA技巧mal...how do I add them?

Currently, my code is:

orderTotal += cartItem.Count * storeDB.Designs.Select(p => p.Price);

// countItem.Count = int
// storeDB.select = decimal

How do I add these? I've tried type casting every which way. Any help is appreciated!

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.Select() returns a collection, which can't be cast to the operand of a multiplication, even if it only contains one item. Take a look at FirstOrDefault() and its kin, which return scalars.

If you're expecting more than one value, you'll need to aggregate Designs with something like Sum() before multiplying the result.

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The result of storeDB.Designs.Select(p => p.Price) is not a decimal. It is an IEnumerable<decimal>. Your logic should look something like this:

 orderTotal += cartItem.Count * 
               storeDb.Designs.First(d => d.Id == cartItem.Id).Price;

Keep in mind that First will throw if there is not an item in the database with the right id ( cartItem.Id).