SQL server management studio subquery

Question

I am trying to run this subquery in SQL Server management Studio 2016 but it errors. It works in MySQL. Please advise:

select count(distinct company) 
from 
(
select company, sum(net_value_gbp) as last2yr_spend 
from Orders 
where bill_date >='01-Jan-2016' 
group by company)
where last2yr_spend >50

Answer 1

alias your subquery like as below

SELECT COUNT(DISTINCT company)
FROM
(
    SELECT company,
           SUM(net_value_gbp) AS last2yr_spend
    FROM Orders o
    WHERE bill_date >= '01-Jan-2016'
    GROUP BY company
) A
WHERE A.last2yr_spend > 50;

Answer 2

Do it like below :

select count(distinct company) 
from 
( select company, sum(net_value_gbp) as last2yr_spend 
from Orders 
where bill_date >= '01-Jan-2016' 
group by company ) 
AS T1
where T1.last2yr_spend > 50

You have to use an ALIAS for the sub query in sql server.

Answer 3

The alias is one issue. But, you should write the query like this:

select count(*) 
from (select company, sum(net_value_gbp) as last2yr_spend 
      from Orders  o
      where bill_date >= '2016-01-01'
      group by company
     ) c
where last2yr_spend > 50;

Notes:

• Note the alias for the subquery (your immediate problem).
• COUNT(DISTINCT) is not needed. The subquery returns one row per company. COUNT(DISTINCT) incurs extra overhead, so a simple COUNT(*) is sufficient.
• The date format uses the ISO-standard YYYY-MM-DD. SQL Server understands this format for most internationalization settings (for 100% completeness, you can drop the hyphens but I like them for readability).
• You would only want COUNT(company) (instead of COUNT(*) ) if company were ever NULL *and you did not want to count it.

Answer 4

select count(company) 
from 
(
select company, sum(net_value_gbp) as last2yr_spend 
from Orders 
where bill_date >='01-Jan-2016' 
group by company
having sum(net_value_gbp) > 50) as T1

Answer 5

An alternative to subqueries is CTE, which I find slightly more readable. Something like the following:

    ;with orders_by_comp as (
          select company, sum(net_value_gbp) as last2yr_spend 
          from Orders  o
          where bill_date >= '2016-01-01'
          group by company)
    select count(distinct company) 
    from orders_by_comp 
    where last2yr_spend > 50;

Answer 6

You can do the filtration on the sum using having like this:

with cte
AS
(
    select company
    from Orders 
    where bill_date >='01-Jan-2016' 
    group by company
    having sum(net_value_gbp) > 50
) 
select count(distinct company)
from cte;