Complex T-SQL Statement - sql

Question

I am not the best SQL programmer so I am basically asking someone for help writing a query that will get my desired result. Here is the table structure for the scope of the query.
CREATE TABLE [dbo].[tblOverNightPermissions] (
[DateAndTime] DATETIME NULL,
[Address] NVARCHAR (200) NULL,
[Direction] NVARCHAR (102) NULL,
[NoOfDays] INT NULL,
[UserID] INT NOT NULL,
[OverNightID] INT IDENTITY (1, 1) NOT NULL,
[Exempt] INT NULL,
[Beat] INT NULL,
CONSTRAINT [PrimaryKey_1fd244dd-bfd8-4998-8439-4d7d7893d387] PRIMARY KEY CLUSTERED ([OverNightID] ASC),
CONSTRAINT [FK_tblOverNightPermissions_0] FOREIGN KEY ([UserID]) REFERENCES [dbo].[tblUsers] ([UserID])
);
CREATE TABLE [dbo].[tblOverNightToVehicles] (
[OverNightID] INT NOT NULL,
[VehicleID] INT NOT NULL,
[ID] INT IDENTITY (1, 1) NOT NULL,
CONSTRAINT [PrimaryKey_b433eaad-fb12-493c-9302-3f3bd9bd74e3] PRIMARY KEY CLUSTERED ([ID] ASC),
CONSTRAINT [FK_tblOverNightToVehicles_0] FOREIGN KEY ([OverNightID]) REFERENCES [dbo].[tblOverNightPermissions] ([OverNightID]) ON DELETE CASCADE ON UPDATE CASCADE,
CONSTRAINT [FK_tblOverNightToVehicles_1] FOREIGN KEY ([VehicleID]) REFERENCES [dbo].[tblVehicles] ([VehicleID]) ON DELETE CASCADE ON UPDATE CASCADE
);
What I want to do is select record from tblOverNightPermissions and group them by month. I also want to count the number of records for that month and grouped by the vehicle ID which is in tblOverNightToVehicles. The goal is to run a check to make sure there have not been more than 5 overnightpermissions per vehicle id per month. It gets kind of tricky because the database design is not sound. As you can see, the NoOfDays field in the tblOvernightPermissions makes things complicated. Instead of there always being a set number of records per month, users have the ability to select up to 5 consecutive days of parking. So if I park today and select 5 days my record entry will look like this
DateAndTime = 5/8/2014
Address = x
Direction = S
NoOfDays = 5
UserId = 1
OvernightId = 1
Exempt = 0
Beat = 2
That means, for the month I will only have one physical record in tblOverNightPermissions that represents 5 days of parking. I could just as easily create 5 records in the table to signify 5 days of parking and thats where the issue comes in. Writing conditionals in TSQL to take into account if a record has NoOfDays > 1 add that to the count of the physical records for the month.
Here are the scripts to populate your databases
Script to populate tblOvernightPermissions https://dl.dropboxusercontent.com/u/62170850/tblOvernightPermissions.txt
Script to populate tblOvernightToVehicles
https://dl.dropboxusercontent.com/u/62170850/tblOverNightToVehicles.txt

Answer 1

SELECT DATEADD(month, DATEDIFF(month, 0, p.DateAndTime), 0) AS [Month],
SUM(p.NoOfDays) As Days
FROM tblOverNightPermissions p
INNER JOIN tblOverNightToVehicles v ON p.OverNightID = v.OverNightID
GROUP BY DATEADD(month, DATEDIFF(month, 0, p.DateAndTime), 0), v.VehicleID
HAVING SUM(p.NoOfDays) >= 5