SQL случай сервера, когда или перечисление

Question

У меня есть таблицы что-то вроде:

stuff   type  price 

first_stuff  1  43 
second_stuff 2  46 
third_stuff  3  24 
fourth_stuff 2  12 
fifth_stuff  NULL 90 

И для каждого type материала присваивается описание, которое не хранится в БД

1 = Bad 
2 = Good 
3 = Excellent 
NULL = Not_Assigned 

Все, что я хочу возвращать таблицу, в которой каждый counttype отдельно, что-то вроде:

Description  Count 

Bad    1 
Good    2 
Excellent  1 
Not_Assigned  1 

Answer 1

DECLARE @t TABLE ([type] INT) 

INSERT INTO @t ([type]) 
VALUES (1),(2),(3),(2),(NULL) 

SELECT 
    [Description] = 
     CASE t.[type] 
      WHEN 1 THEN 'Bad' 
      WHEN 2 THEN 'Good' 
      WHEN 3 THEN 'Excellent' 
      ELSE 'Not_Assigned' 
     END, t.[Count] 
FROM (
    SELECT [type], [Count] = COUNT(*) 
    FROM @t 
    GROUP BY [type] 
) t 
ORDER BY ISNULL(t.[type], 999) 

выход -

Description Count 
------------ ----------- 
Bad   1 
Good   2 
Excellent 1 
Not_Assigned 1 

Answer 2

Надежда, это помогает.

SELECT ISNULL(D.descr, 'Not_Assigned'), 
     T2.qty 
FROM 
    (SELECT T.type, 
      COUNT(*) as qty 
    FROM Table AS T 
    GROUP BY type) AS T2 
    LEFT JOIN (SELECT 1 as type, 'Bad' AS descr 
       UNION ALL 
       SELECT 2, 'Good' 
       UNION ALL 
       SELECT 3, 'Excellent') AS D ON D.type = T2.type 

Answer 3

Если вы используете Sql server 2012+ использовать этот

SELECT 
    [Description] = coalesce(choose (t.[type],'Bad','Good' ,'Excellent'), 'Not_Assigned'), 
    t.[Count] 
FROM (
    SELECT [type], [Count] = COUNT(*) 
    FROM yourtable 
    GROUP BY [type] 
) t 

Answer 4

;WITH CTE_TYPE 
    AS (SELECT DESCRIPTION, 
       VALUE 
     FROM (VALUES ('BAD', 
       1), 
         ('GOOD', 
       2), 
         ('EXCELLENT', 
       3))V(DESCRIPTION, VALUE)), 
    CTE_COUNT 
    AS (SELECT C.DESCRIPTION, 
       Count(T.TYPE) TYPE_COUNT 
     FROM YOUR_TABLE T 
       JOIN CTE_TYPE C 
        ON T.TYPE = C.VALUE 
     GROUP BY TYPE, 
        DESCRIPTION 
     UNION ALL 
     SELECT 'NOT_ASSIGNED' AS DESCRIPTION, 
       Count(*)  TYPE_COUNT 
     FROM YOUR_TABLE 
     WHERE TYPE IS NULL) 
SELECT * 
FROM CTE_COUNT