SQL Server 2012：我在使用If-Else if-Else块时遗漏了什么？

Question

总的来说，我试图查看审核表，看看是否已经处理了特定的日期范围。 在这种特定情况下， @fstartrangedate将为NULL，因为尚未找到2016-11-01开始日期。 这应该是主要的其他条件。 @superceded应设置为0， @type （sumtype）应设置为WEEKLY， @days应设置为7。

我做到了正确的主要条件。 甚至将它设置为Weekly - 然而，某种程度上@type被设置为SPECIAL。

有人可以看看@this。 我可能做了一些非常愚蠢的事，但我只是没有看到它。

这是代码：

-- 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declare @superceded bit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     -- we found an existing range which will be superseded by this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     set @superceded = 1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  set @superceded = 0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

以下是执行时的调试输出消息：

 (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)*

以下是执行时的变量输出消息：

Answer 1

让我向您介绍我的好友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;

---

错误在这里：

 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' 

具有讽刺意味的是，如果您没有使用这些print语句调试代码，那么您就不会遇到（发现？）错误。

rextester演示以显示错误，以及begin/end将如何修复它： http ：//rextester.com/CSUM92647