SQL Server 2012: am I missing something when working with an If-Else if-Else block?

Question

Overall I am attempting to look through an auditing table to see if a specific date range has already been processed. In this specific case, @fstartrangedate will be NULL, as the 2016-11-01 start date has not been found. This should make it to the main else condition. @superceded should be set to 0, @type (sumtype) should be set to WEEKLY, @days should be set to 7.

I make it to the correct main else condition. Even make it to Weekly -- and yet, somehow @type is set to SPECIAL.

Can someone please take a look @this. I've probably done something really silly, but I just don't see it.

Here's the code:

-- determine if this is a daily, weekly, monthly or special run
declare @superceded bit
declare @type varchar(50)
declare @foundSameStartDate bit
declare @days int
declare @vdays int
declare @fLoadId int

-- incoming parameters
declare @startrangedate date
declare @endrangedate date

-- found startdate
declare @fstartrangedate date

--debug
select @fstartrangedate as fstartrangedate

-- validation test --
declare @vstartrangedate date
declare @vendrangedate date

set @startrangedate = cast('2016-11-01' as date);
-- debug
select @startrangedate as startrangedate

set @endrangedate = cast('2016-11-08' as date);

select 
    @fstartrangedate = StartRangeDateTime,
    @fLoadId = LoadId
from 
    FleetMatching.Audit_LoadTracker
where 
    StartRangeDateTime IN (select StartRangeDateTime
                           from FleetMatching.Audit_LoadTracker
                           where IsSuperceded = 0
                             and IsLoadCompleted = 1
                             and StartRangeDateTime = @startrangedate)

 -- debug
 select @fstartrangedate as fstartrangedate

 IF(@fstartrangedate is not null)
 BEGIN
     print 'found start date does = startdate'
     -- valid start/end dates for a full month

     select @vstartrangedate = dateadd(month, datediff(month, 0, @startrangedate), 0) 
     select @vendrangedate = dateadd(day, -1, dateadd(month, datediff(month, -1, @startrangedate), 0))

     select @days =  datediff(day, @startrangedate, @endrangedate)
     select @vdays = datediff(day, @vstartrangedate, @vendrangedate)

     -- we found an existing range which will be superseded by this
     -- execution/load
     set @superceded = 1

  -- debug
  select @days as [Days]
  select @type as SumType

  if(@days = 1)
    set @type = 'DAILY'
  else if(@days = 7)
    set @type = 'WEEKLY'
  else if((@days >= 27) AND (@days <= 31))
    set @type = 'MONTHLY'
  else
    print 'found condition-special'
    set @type = 'SPECIAL'
  END
ELSE
 Begin
  print 'Reached MAIN-IF Else Condition'
  print 'found start date does NOT .eq. startdate'
  set @superceded = 0
  select @days = datediff(day,@startrangedate,@endrangedate)
  -- debug
  select @days as [Days]
  select @type as SumType

  if(@days = 0)
    begin
     print 'daily as 0'
     set @type = 'DAILY'
    end
  else if(@days = 7)
    begin
      print 'weekly as 7';
      set @type = 'WEEKLY';
    end
  else if(@days >= 28 AND @days <= 31)
   begin
     print 'monthly as 28->31'
     set @type = 'MONTHLY'
   end
  else
    print 'else condition=special'
    set @type = 'SPECIAL'
 END

 -- DEBUG
 select @superceded as IsSuperceded
 select @type as SumType

Here are the debug output messages when executed:

 (1 row(s) affected)

 (1 row(s) affected)

 (1 row(s) affected)

 Reached MAIN-IF Else Condition

 found start date does NOT .eq. startdate

 (1 row(s) affected)

 (1 row(s) affected)

 weekly as 7

 (1 row(s) affected)

 (1 row(s) affected)*

Here are the variable output messages when executed:

Answer 1

Let me introduce you to my buddy case!

set @type = case 
     when @days = 0 then 'Daily'
     when @days = 7 then 'Weekly'
     when @days >=28 and @days <= 31 then 'Monthly'
     else 'Special'
     end;

---

The error is here:

if (@days = 0)
 begin
  print 'daily as 0'
  set @type = 'DAILY'
 end
 else if (@days = 7)
 begin
  print 'weekly as 7';
  set @type = 'WEEKLY';
 end
 else if (@days >= 28 and @days <= 31)
 begin
  print 'monthly as 28->31'
  set @type = 'MONTHLY'
 end
 else
  print 'else condition=special' /* < ----- 
                       without begin and end, else stops after the print 
                       and the following `set` is outside of the flow control */
 set @type = 'SPECIAL'

Ironically, you would not have had (found?) that error if you were not debugging your code with those print statements.

rextester demo to show the error, and how begin/end would fix it: http://rextester.com/CSUM92647