All hour of the day

Question

In my sql query, I count the number of orders at every hour of the day. My query looks something like this:

SELECT   COUNT(dbo.Uputa.ID),{ fn HOUR(dbo.Orders.Date) } AS Hour
FROM      Orders       
WHERE dbo.Orders.Date BETWEEN '2011-05-01' AND '2011-05-26' 
GROUP BY { fn HOUR(dbo.Orders.Date) }
ORDER BY Hour

My problem is that the query only returns the existing hours in dbo.Orders.Date.
For instance:

Number   Hour
12         3
12         5

I want to return all the watches as follows:

 Number      Hour
    0          0
    0          1
    0          2
    12         3
    0          4
    12         5
   ...
    0          23

Does anyone have any ideas how to do this?

Answer 1

Use a common table expression to create all hours, then the left joins your grouped totals to get the result.

with mycte as
(
    SELECT 0 AS MyHour
    UNION ALL
    SELECT MyHour + 1
    FROM mycte 
    WHERE MyHour + 1 < 24
)
SELECT mycte.MyHour, COALESCE(OrderCount,0) FROM mycte
LEFT JOIN 
(
    SELECT  COUNT(dbo.Uputa.ID) AS OrderCount,{ fn HOUR(dbo.Orders.Date) } AS MyHour
    FROM    Orders       
    WHERE   dbo.Orders.Date BETWEEN '2011-05-01' AND '2011-05-26' 
    GROUP BY { fn HOUR(dbo.Orders.Date) }
) h
ON
  h.MyHour = mycte.MyHour;

Answer 2

A 'table table' (SQL, , ), , ; , 0 23 , , CTE .

SELECT   COUNT(dbo.Uputa.ID),n.number AS Hour
FROM     (select number from numbers where number between 0 and 23) n 
             left join Orders o on n.number={ fn HOUR(dbo.Orders.Date) }
WHERE dbo.Orders.Date BETWEEN '2011-05-01' AND '2011-05-26' 
GROUP BY n.number
ORDER BY n.number

( , , .)

Answer 3

CTE, JOIN , .

SQL

;WITH q (Number, Hour) AS (
    SELECT  0, 1
    UNION ALL
    SELECT  q.Number, q.Hour + 1
    FROM    q
    WHERE   q.Hour < 23
)
SELECT  COALESCE(o.Number, q.Number)
        , q.Hour
FROM    q
        LEFT OUTER JOIN (
            SELECT   COUNT(dbo.Uputa.ID),{ fn HOUR(dbo.Orders.Date) } AS Hour
            FROM      Orders       
            WHERE dbo.Orders.Date BETWEEN '2011-05-01' AND '2011-05-26' 
            GROUP BY { fn HOUR(dbo.Orders.Date) }
        ) o ON o.Hour = q.Hour
ORDER BY 
        q.Hour      

Script

;WITH Orders (Number, Hour) AS (
    SELECT 12, 3
    UNION ALL SELECT 12, 5
)
, q (Number, Hour) AS (
    SELECT  0, 1
    UNION ALL
    SELECT  q.Number, q.Hour + 1
    FROM    q
    WHERE   q.Hour < 23
)
SELECT  COALESCE(o.Number, q.Number)
        , q.Hour
FROM    q
        LEFT OUTER JOIN Orders o ON o.Hour = q.Hour