--Stored procedure to create loan
CREATE PROCEDURE uspCreateLoan (@userID INT, @itemID INT, @employeeID INT)
AS
BEGIN
DECLARE @currentLoans INT = dbo.fnGetUserLoans(@userID) --Declaring variable currentLoans as the current amount of active loans from the user
IF (SELECT maxItems FROM LibraryUser WHERE userID = @userID) > @currentLoans --Check if user has not surpassed max items they may loan at once
BEGIN
    IF (SELECT categoryName FROM Category --Do not let the user loan reference literature
                JOIN Item ON Item.CategoryID = Category.categoryID
                WHERE Item.itemID = @itemID) NOT LIKE 'Reference Literature'
        BEGIN
            IF (SELECT avaliable FROM Item WHERE itemID = @itemID) = 1 --If the item the user wants is avaliable then create a loan for that item
            BEGIN
                DECLARE @dateAdd INT --Declaring dateadd and dueDate variables
                DECLARE @dueDate DATE
                SET @dateAdd = (SELECT maxLoanAllowance FROM Category --Setting dateAdd to the max amount of time you can loan that item
                    JOIN Item ON Item.CategoryID = Category.categoryID
                    WHERE Item.itemID = @itemID)
                SET @dueDate = GETDATE()+DATEADD(week,@dateAdd,@itemID) --calculating the due date by adding the current date with dateAdd

                INSERT INTO Loan (userID,employeeID,dueDate,itemID,returned) --Creating a new row in Loan with arguments supplied by the caller
                VALUES (@userID,@employeeID,@dueDate,@itemID,0)
                PRINT 'Thank you!'
                UPDATE Item SET avaliable = 0 WHERE itemId = @itemID --Setting item as unavaliable so it may not be loaned.
                RETURN
            END
            PRINT 'Unsuccessful, Item Unavaliable.'
            RETURN
        END
        PRINT 'You may not loan reference literature'
        RETURN
    END
    PRINT 'You have reached your loan limit. Return past loans.'
END
GO