添加行时在列中重新编号 sql

Question

一个table喜欢

create table Stations_in_route
(
ID_station_in_route int primary key,
ID_route int,
ID_station int,
Number_in_route int not null
)

有如下触发器在路由添加新行后改变Number_in_route列中的值。路由中的号码列表必须保持一致。

create trigger stations_in_route_after_insert on Stations_in_route
after insert
as

if exists
(select *from Stations_in_route
where Stations_in_route.ID_station_in_route not in (select ID_station_in_route from inserted)
and Stations_in_route.ID_route in (select ID_route from inserted) 
and Stations_in_route.Number_in_route in (select Number_in_route from inserted))

begin
update Stations_in_route
set Number_in_route = Number_in_route + 1
where Stations_in_route.ID_station_in_route not in (select ID_station_in_route from inserted)
and Stations_in_route.ID_route in (select ID_route from inserted) 
and Stations_in_route.Number_in_route >= (select Number_in_route from inserted where Stations_in_route.ID_route = inserted.ID_route)
end

如果执行插入一个 ID_route，此触发器将抛出错误：

Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

例如，

Insert into Stations_in_route values(25, 4, 11, 3),(26, 4, 10, 5)

如何修复？

ID_station_in_route	ID_route	ID_station	Number_in_route
1	4	1	1
2	4	2	2
3	4	3	3
4	4	4	4
5	4	5	5
6	4	6	6
7	4	7	7
8	4	8	8

希望添加后的列表会变成这样

ID_station_in_route	ID_route	ID_station	Number_in_route
1	4	1	1
2	4	2	2
25	4	11	3
3	4	3	4
26	4	10	5
4	4	4	6
5	4	5	7
6	4	6	8
7	4	7	9
8	4	8	10

这不是全部table，因为还有其他路线

Answer 1

根据要求，当您向路线添加新停靠点时，您需要将它们正确插入到所需的顺序中，并将所有现有停靠点从该点向前推，以便保持连续的顺序。当你插入一行时，这不是很难（只是 number_in_route + 1 where number_in_route > new_number_in_route），但是当你插入更多行时，你基本上需要将整个后续停止点集推 1 for each 新行。为了说明这一点，假设您从这个开始：

如果我们插入两个新行，比如：

INSERT dbo.Stations_in_route
(
  ID_station_in_route,
  ID_route,
  ID_station,
  Number_in_route
)
VALUES (25, 4, 11, 3),(26, 4, 10, 5);
-- add a stop at 3 ^              ^
----------------- add a stop at 5 ^

我们可以通过将其放慢为单独的步骤来说明这一点。首先，我们需要在位置 #3 添加这一行：

我们通过将所有行 > 3 向下推 1 来做到这一点：

但是现在当我们在位置 #5 添加这一行时：

那是新位置 #5，在之前的班次之后，所以它看起来像这样：

我们可以使用以下触发器来执行此操作，这可能比必须的要复杂一些，但恕我直言，这比可能需要的繁琐循环要好。

CREATE TRIGGER dbo.tr_ins_Stations_in_route ON dbo.Stations_in_route
FOR INSERT AS
BEGIN
    ;WITH x AS 
    (
      SELECT priority = 1, *, offset = ROW_NUMBER() OVER 
        (PARTITION BY ID_route ORDER BY Number_in_route)
      FROM inserted AS i
      UNION ALL 
      SELECT priority = 2, s.*, offset = NULL FROM dbo.Stations_in_route AS s
        WHERE s.ID_route IN (SELECT ID_route FROM inserted)
    ), 
    y AS 
    (
      SELECT *, rough_rank = Number_in_route 
          + COALESCE(MAX(offset) OVER (PARTITION BY ID_Route 
            ORDER BY Number_in_route ROWS UNBOUNDED PRECEDING),0) 
          - COALESCE(offset, 0),
        tie_break = ROW_NUMBER() OVER 
          (PARTITION BY ID_route, ID_station_in_route ORDER BY priority)
      FROM x
    ),
    z AS 
    (
      SELECT *, new_Number_in_route = ROW_NUMBER() OVER 
        (PARTITION BY ID_Route ORDER BY rough_rank, priority) 
      FROM y WHERE tie_break = 1
    )
    UPDATE s SET s.Number_in_route = z.new_Number_in_route
      FROM dbo.Stations_in_route AS s
      INNER JOIN z ON s.ID_route = z.ID_route
        AND s.ID_station_in_route = z.ID_station_in_route;
END

工作示例db<>fiddle

我已经多次提到您可能想要处理新行的联系，例如如果插入恰好是：

Insert into Stations_in_route values(25, 4, 11, 3),(26, 4, 10, 3)

为此，您可以在此子句中添加额外的打破平局的标准：

  new_Number_in_route = ROW_NUMBER() OVER 
    (PARTITION BY ID_Route ORDER BY rough_rank, priority)

例如：

  new_Number_in_route = ROW_NUMBER() OVER 
    (PARTITION BY ID_Route ORDER BY rough_rank, priority, 
     ID_station_in_route DESC)

Answer 2

我无法通过问题中的测试 code/data 重现异常，但是我猜问题出在触发器中的这段代码上：

AND Stations_in_route.Number_in_route >= 
(
SELECT Number_in_route
FROM inserted
WHERE Stations_in_route.ID_route = inserted.ID_route
)

那里的引擎将隐含地期望 >= 运算符右侧的子查询到 return 标量结果（单行，单列结果），但是插入的 table 是实际上，一个 table... 可能包含多个记录（如示例中概述的多行 insert/update/etc.type 语句中的情况）。鉴于该子查询中的过滤器（即 WHERE 子句）不能保证是唯一的（ID_route 似乎不是唯一的，并且在您的示例中，您有一个 insert 语句实际上插入了具有相同的多行ID_route 值），那么查询肯定有可能 return 一个非标量结果。

要解决此问题，您需要调整该子查询以保证标量值（单行和单列）的结果。您已经使用选择器保证单列...现在您需要添加逻辑来保证单个 result/record 。这可能包括以下一项或多项（也可能包括其他内容）：

将选定的 Number_in_route 列包装在聚合函数中（即 MAX() 或许？）
添加带有 ORDER BY 的 TOP 1 以获得您要与之比较的记录
向 WHERE 子句添加额外的过滤器以确保return编辑

添加行时在列中重新编号 sql

renumbering in a column when adding a row sql

sql

database

sql-server

triggers