Question

如何从此表单中转换表格：

S_ID          SUBJECT          MARK
1             English          90
1             Math             40
1             Computer         30
2             English          85
2             Math             10
2             Computer         06
3             English          10
3             Math             20
3             Computer         40

到此表格

S_ID       English        Math         Computer
1          90             40           30
2          85             10           06
3          10             20           40

使用SQL代码，

我正在使用MS Access 2010，

谢谢

Answer 1

SELECT S_ID ,
       MAX(CASE WHEN subject = 'English' THEN mark ELSE null END) AS English,
       MAX(CASE WHEN subject = 'Math' THEN mark ELSE null END) AS Math,
       MAX(CASE WHEN subject = 'Computer' THEN mark ELSE null END) AS Computer
FROM myTable
GROUP BY S_ID

Answer 2

您需要一个交叉表查询，该查询将为每个主题生成一列;

TRANSFORM Sum(MARK) AS TotalMark
SELECT 
   S_ID
FROM marks
   GROUP BY S_ID
PIVOT SUBJECT;

Answer 3

如果这是一次性练习，你可以按顺序使用许多语句：类似这样的事情：

insert into new_table
select distinct s_id, 0,0,0
from old_table

然后是一系列更新

update new_table n
set english = (select english from old_table where s_id = n.s_id )
where s_id = n.s_id

MS access 2010 SQL查询帮助

3 个答案: