切换列值

Question

我有2张这样的桌子。

MasterEntries中的列：

  ParishName    AverageMark    
  Hanover         50.00
  Manchester      65.00
  Andrew          70.00

MasterScoreSheet中的列：

 Hanover      Manchester    [St.Andrew]
 50.00        65.00         70.00

我希望将AverageMark中的MasterEntries列值变成相应列的值，如下所示：

 Hanover      Manchester    Andrew
 50.00        65.00         70.00

我该怎么做？

Answer 1

如果值固定为"Hanover","Manchester","Andrew"，并且只有3行，则可以使用PIVOT()方法：

SELECT * 
FROM MasterEntries
     PIVOT(MAX(AverageMark) FOR ParishName IN ("Hanover","Manchester","Andrew")) AS AvgMark

• SqlFiddle

Answer 2

是否要将这些值插入表MasterScoreSheet中？
您可以这样做：

insert into MasterScoreSheet (Hannover, Manchester, Andrew)
select
  (select AverageMark from MasterEntries where ParishName = 'Hannover'),
  (select AverageMark from MasterEntries where ParishName = 'Manchester'),
  (select AverageMark from MasterEntries where ParishName = 'Andrew');

请参见demo。

Answer 3

我将使用条件聚合编写此查询：

url="www.google.com"

if expr.match(url):
    print("It is valid")