Question

我有这个查询

SELECT semester, COUNT(id) AS total, RIGHT(RTRIM(semester), 4) AS year 
FROM TextbookReservation 
WHERE (semester IS NOT NULL) 
AND (semester <> '')
AND (semester <> 'SM2008') 
AND semester <> 'SU2008') 
GROUP BY semester ORDER BY year, semester DESC

产生类似这样的东西：

semester  total year
SP2006    2277  2006
FA2006    4367  2006
SP2007    2893  2007
FA2007    5624  2007
SP2008    4083  2008
FA2008    6451  2008

我想返回这样的内容：

year  totalSpring totalFall
2006  2277        4367
2007  2893        5624
2008  4083        6451

关于如何处理此查询的任何想法？谢谢！

Answer 1

没有PIVOT表，因为您没有指定版本：

SELECT [year], 
sum(case WHEN left(semester,2)='SP' then total ELSE 0 END) as totalSpring ,
sum(case WHEN left(semester,2)='FA' THEN total else 0 end) as totalFall
from (

       SELECT semester
            , count(id) AS total
            , right(RTRIM(semester), 4) AS year
       FROM
           TextbookReservation
       WHERE
           semester IS NOT NULL
           AND semester <> ''
           AND semester <> 'SM2008'
           AND semester <> 'SU2008'
       GROUP BY
           semester 
) t
GROUP BY t.[year]
order by t.[year]

Answer 2

您要做的是创建pivot。版本2005和更高版本的SQL具有内置命令来透视数据。

您能指定数据库使用的SQL Server版本吗？

PS。您也可以使用2005年之前的Case语句执行此操作。由于您的示例仅有两个学期的离散值，我将使用该方法提供答案。

 Select year, SUM(TotalSpring), SUM(TotalFall) From
(select RIGHT(RTRIM(semester), 4) AS year, case LEFT(semester,2) when  'SP' then 1 else 0 end TotalSpring, case LEFT(semester,2) when  'FA' then 1 else 0 end TotalFall
from TextbookReservation
WHERE (semester IS NOT NULL) 
AND (semester <> '') 
AND (semester <> 'SM2008') 
AND semester <> 'SU2008') as t1
group by year
order by year

Answer 3

其他答案的简化版本：

SELECT 
    RIGHT(RTRIM(semester), 4) year, 
    COUNT(CASE WHEN left(semester,2)='SP' then id else null end) totalSpring,
    COUNT(CASE WHEN left(semester,2)='FA' then id else null end) totalFall
FROM TextbookReservation
WHERE (semester IS NOT NULL) 
      AND (semester <> '')
      AND (semester <> 'SM2008') 
      AND (semester <> 'SU2008') 
GROUP BY RIGHT(RTRIM(semester), 4)
ORDER BY RIGHT(RTRIM(semester), 4) DESC

这里是测试脚本：

CREATE TABLE #TextbookReservation
(
    semester VARCHAR(6),
    id INT  
)

INSERT INTO #TextbookReservation VALUES ('SP2006', 1)
INSERT INTO #TextbookReservation VALUES ('SP2006', 2)
INSERT INTO #TextbookReservation VALUES ('SP2006', 3)
INSERT INTO #TextbookReservation VALUES ('SP2006', 4)
INSERT INTO #TextbookReservation VALUES ('SP2006', 5)
INSERT INTO #TextbookReservation VALUES ('FA2006', 1)
INSERT INTO #TextbookReservation VALUES ('FA2006', 2)
INSERT INTO #TextbookReservation VALUES ('FA2006', 3)
INSERT INTO #TextbookReservation VALUES ('SP2007', 1)
INSERT INTO #TextbookReservation VALUES ('SP2007', 2)
INSERT INTO #TextbookReservation VALUES ('FA2007', 1)
INSERT INTO #TextbookReservation VALUES ('FA2007', 2)
INSERT INTO #TextbookReservation VALUES ('FA2007', 3)
INSERT INTO #TextbookReservation VALUES ('FA2007', 4)
INSERT INTO #TextbookReservation VALUES ('FA2007', 5)

SELECT 
    RIGHT(RTRIM(semester), 4) year, 
    COUNT(CASE WHEN left(semester,2)='SP' then id else null end) totalSpring,
    COUNT(CASE WHEN left(semester,2)='FA' then id else null end) totalFall
FROM #TextbookReservation
WHERE (semester IS NOT NULL) 
      AND (semester <> '')
      AND (semester <> 'SM2008') 
      AND (semester <> 'SU2008') 
GROUP BY RIGHT(RTRIM(semester), 4)
ORDER BY RIGHT(RTRIM(semester), 4) DESC


DROP TABLE #TextbookReservation

具有内部联接的SQL计数

3 个答案: