如何根据另外两列填充列

Question

我的表格LessonHour包含空Number列。

TABLE [dbo].[LessonHour]
(
    [Id] [uniqueidentifier] NOT NULL,
    [StartTime] [time](7) NOT NULL,
    [EndTime] [time](7) NOT NULL,
    [SchoolId] [uniqueidentifier] NOT NULL,
    [Number] [int] NULL
)

如何为每个Number填写LessonHour表，以便按顺序上课时数？ LessonHours无法互相交叉。每所学校都定义了自己的课时架构。

示例数据集 http://pastebin.com/efWCtUbv

我该怎么做：

1. 按SchoolId和StartTime排序
2. 使用光标插入行的下一个数字，每次SchoolId更改时从1开始。

编辑：

使用光标解决方案

select -- top 20
        LH.[Id],
        [StartTime],
        [EndTime],
        [SchoolId]
into #LH
from
    LessonHour as LH
    join RowStatus as RS on LH.RowStatusId = RS.Id
where 
    RS.IsActive = 1

select * from #LH order by SchoolId, StartTime

declare @id uniqueidentifier, @st time(7), @et time(7), @sid uniqueidentifier
declare @prev_sid uniqueidentifier = NEWID()
declare @i int = 1
declare cur scroll cursor for
select * from #LH order by SchoolId, StartTime
open cur;
fetch next from cur into @id, @st, @et, @sid
while @@FETCH_STATUS = 0
begin
    --print @prev_sid
    if @sid <> @prev_sid
    begin
        set @i = 1
    end

    update LessonHour set Number = @i where Id = @id

    print @i
    set @i = @i + 1

    set @prev_sid = @sid
    fetch next from cur into @id, @st, @et, @sid
end;
close cur;
deallocate cur;

drop table #LH

这是我在http://pastebin.com/iZ8cnA6w

之后的结果

Answer 1

合并StackOverflow问题中的信息SQL Update with row_number()和 How do I use ROW_NUMBER()?：

with cte as (
    select number, ROW_NUMBER() OVER(partition by schoolid order by starttime asc) as r from lessonhour
)
update cte
set number = r

Answer 2

这会有效吗

CREATE TABLE [dbo].[LessonHour]
(
    [Id] [uniqueidentifier] NOT NULL,
    [StartTime] [time](7) NOT NULL,
    [EndTime] [time](7) NOT NULL,
    [SchoolId] [uniqueidentifier] NOT NULL,
    [Number] AS DATEDIFF(hour,[StartTime],[EndTime])
)

因此，如果我正确理解了这个问题，您需要一个计算列，该列接收[StartTime]和[EndTime]的值，并将该课程的小时数作为int返回。上面的表定义应该可以解决问题。