Обновить динамическое предложение where, используя счетчик циклов?

Question

Пожалуйста, проверьте этот запрос:

declare @T table 
(
FirstColumn datetime primary key, 
S_E1 float 
) 

insert into @T(FirstColumn, S_E1) values 
('2012-01-01T00:00:01', 1), 
('2012-01-01T00:00:02', 2), 
('2012-01-01T00:00:03', 3), 
('2012-01-01T00:00:04', 4), 
('2012-01-01T00:00:05', 5), 
('2012-01-01T00:00:06', 6) 

declare @Take varchar = '1' 
declare @StartDate varchar(10)='2012-01-01T00:00:01' 
declare @EndDate varchar(10) = '2012-01-01T00:00:06' 
declare @count varchar(Max) 
DECLARE @SQL nvarchar(Max) 
set @count = (select count(FirstColumn) from @T Where FirstColumn Between ''+@StartDate+'' and ''+@EndDate+'') 

set @SQL =' select S_E1 from @T where S_E1 ='+ @Take+'' 

BEGIN try 
while(CAST(@Take AS int) < CAST(@count AS int)) 
Begin 

    print @SQL; 
    set @Take = CONVERT(varchar,CAST(@Take AS int)+1) 

end 
END TRY 
BEGIN CATCH 
    select ERROR_MESSAGE() as errormessage 
END CATCH 

Проблема: В приведенном выше запросе я не могу обновить переменную @Take value.Please дайте мне знать, где я иду по неправильному пути.

Answer 1

Изменил некоторые типы данных и переместил назначение @SQL в цикл.

declare @T table 
(
FirstColumn datetime primary key, 
S_E1 float 
) 

insert into @T(FirstColumn, S_E1) values 
('2012-01-01T00:00:01', 1), 
('2012-01-01T00:00:02', 2), 
('2012-01-01T00:00:03', 3), 
('2012-01-01T00:00:04', 4), 
('2012-01-01T00:00:05', 5), 
('2012-01-01T00:00:06', 6) 

declare @Take int = 1 
declare @StartDate datetime = '2012-01-01T00:00:01' 
declare @EndDate datetime = '2012-01-01T00:00:06' 
declare @count int 
declare @SQL nvarchar(Max) 

set @count = (select count(FirstColumn) 
       from @T 
       where FirstColumn Between @StartDate and @EndDate) 

begin try 
    while @Take <= @count 
    begin 

    set @SQL =' select S_E1 from @T where S_E1 ='+ cast(@Take as varchar(10))+'' 
    print @SQL; 

    set @Take = @Take + 1 
    end 
end try 
begin catch 
    select error_message() as errormessage 
end catch