Question

I’m not sure why the following subquery doesn’t work in SQL Server, when I run the subquery by itself it works just fine, but as soon as I add

Select * from ([subquery]) as table1

the query doesn’t run, SQL Server returns an error saying I have incorrect syntax near the keyword ‘if’, what syntax error exists here and how come it will work just fine otherwise?

Any pointers?

select * from (

    if datepart(MONTH, getdate()) >= MONTH('1/February/0000') 
    --after february we want the next years semesters, 

        begin
        select top 3 sem_name from semester_dates
         where datepart(year, start_date) < datepart(YEAR, getdate()) and sem_name not like 'summer%'
        end

    else 
        begin
        select top 3 sem_name from semester_dates  sd
        where datepart(year, start_date) >= datepart(YEAR, getdate()) and sem_name not like 'summer%' 
        end

    ) table1

Answer 1

You may want to consider moving your if/else logic into a table valued function. Something like this perhaps. Note, I didn’t check your logic, I just re-used this. You may need to adjust the code below accordingly:

CREATE FUNCTION SemesterNames
(
  @ReferenceDate datetime
)
RETURNS @dates table 
(
  sem_name nvarchar(50) --check the data type
)
AS
BEGIN
  if datepart(MONTH, @ReferenceDate) >= MONTH('1/February/0000') 
    --after february we want the next years semesters, 
    INSERT INTO @dates (sem_name)
    select top 3 sem_name from semester_dates
     where datepart(year, start_date) > datepart(YEAR, @ReferenceDate) and sem_name not like 'summer%'
    end
else 
    INSERT INTO @dates (sem_name)
    select top 3 sem_name from semester_dates  sd
    where datepart(year, start_date) >= datepart(YEAR, @ReferenceDate) and sem_name not like 'summer%' 
END;
GO

SELECT * FROM SemesterNames(GETDATE());