一个投球手不能在板球比赛中连续两次投球

Question

我正在从事板球项目。我有一个 table OverDetails。我想在这个 table.

中插入数据

ID  OverNumber  BowlerID  InningsID
1       1          150          1
2       4          160          1
3       3          165          1
4       2          150          1

Row_1、Row_2 和 Row_3 是合法的。 Row_4 是不合法的，因为一个保龄球手不能在一局中连续两次投球。不必在数据库中连续添加。

我在 SQL 服务器中添加了一个约束。

#Constraint_1

ALTER TABLE OverDetails ADD CONSTRAINT UniqueOverInInning 
UNIQUE(OverNumber, BowlerID, IninngsID);

这个约束非常有效。

我需要这样的支票：

#Constraint_2

ALTER TABLE OverDetails ADD CONSTRAINT UniqueConsecutiveBowlerInOneInning 
CHECK (OverNumber + 1 != OverNumber and BowlerID + 1 != BowlerID 
         and IninngID + 1 != IninngID)

Answer 1

您需要一个函数，它 returns 来自给定 InningID 的最后一个 BowlerID：

    CREATE FUNCTION dbo.GetBowlerID
        ( @InningId INT, @OverNumber INT, @BowlerID INT)
        RETURNS INT
        AS
        BEGIN
        RETURN (SELECT top 1 CASE WHEN
(SELECT BowlerID
    FROM OverDetails 
    WHERE InningsId = @InningId AND OverNumber = @OverNumber - 1 ) = @BowlerID
OR
(SELECT BowlerID
    FROM OverDetails 
    WHERE InningsId = @InningId AND OverNumber = @OverNumber + 1 ) = @BowlerID
THEN 1 else 0 end)
        END

然后你可以把它放入检查约束中：

ALTER TABLE OverDetails ADD CONSTRAINT UniqueConsecutiveBowlerInOneInning 
  CHECK (dbo.GetBowlerID(InningsId, OverNumber, BowlerID)=0)

Answer 2

也许是这个？

create function dbo.chk_fnk (@OverNumber int,  @BowlerID int,  @InningsID int)
returns int
as
begin
return 
      case when
           exists (select * 
                   from dbo.OverDetails
                   where BowlerID = @BowlerID and abs(OverNumber - @OverNumber) = 1 and InningsID = @InningsID)
           then 1
           else 0
      end;  
end;
go

ALTER TABLE dbo.OverDetails ADD CONSTRAINT UniqueConsecutiveBowlerInOneInning 
  CHECK (dbo.chk_fnk(OverNumber,  BowlerID,  InningsID) = 0);

Answer 3

检查约束不能直接引用其他行数据。有一些技术试图使用 UDF 来绕过这个限制，但它们往往效果不佳。特别是在这种情况下，我假设如果第 4 行的插入 also 的 bowlerID 为 165，则应该被阻止，因为这意味着 2 和 3 轮共享一个投球手。

相反，我们可以用一对视图来实现它。我通常将 DRI 放在像这样的视图名称中的某处，以表明它们存在是出于声明引用完整性的原因，而不是因为我打算让人们查询它们。

create table dbo.Bowling (
    ID int not null,
    OverNumber int not null,
    BowlerID int not null,
    InningsID int not null,
    constraint PK_Bowling PRIMARY KEY (ID),
    constraint UQ_Bowling_Overs UNIQUE (OverNumber,InningsID)
)
go
create view dbo.Bowling_DRI_SuccessiveOvers_Odd
with schemabinding
as
    select
        (OverNumber/2) as OddON,
        BowlerID
    from
        dbo.Bowling
go
create unique clustered index UQ_Bowling_DRI_SuccessiveOvers_Odd on dbo.Bowling_DRI_SuccessiveOvers_Odd (OddON,BowlerID)
go
create view dbo.Bowling_DRI_SuccessiveOvers_Even
with schemabinding
as
    select
        ((OverNumber+1)/2) as EvenON,
        BowlerID
    from
        dbo.Bowling
go
create unique clustered index UQ_Bowling_DRI_SuccessiveOvers_Even on dbo.Bowling_DRI_SuccessiveOvers_Even (EvenON,BowlerID)
go
insert into dbo.Bowling(ID,OverNumber,BowlerID,InningsID) values
(1,1,150,1),
(2,4,160,1),
(3,3,165,1)
go
insert into dbo.Bowling(ID,OverNumber,BowlerID,InningsID) values
(4,2,150,1)

最后的插入产生错误：

Msg 2601, Level 14, State 1, Line 37 Cannot insert duplicate key row in object 'dbo.Bowling_DRI_SuccessiveOvers_Even' with unique index 'UQ_Bowling_DRI_SuccessiveOvers_Even'. The duplicate key value is (1, 150). The statement has been terminated.

希望您能看到我用来让这些视图检查您想要的约束的技巧 - 它的设置是为了使行与其（逻辑上的，基于 OrderNumber）后继者或前任者配对基于使用整数数学将 OrderNumber 除以二。

然后我们对这些对应用唯一约束，包括 BowlerID。仅当同一个投球手连续两次投球时，我们才会生成具有相同 (OddON/EvenON) 和 BowlerID 值的不止一行。

一个投球手不能在板球比赛中连续两次投球

One Bowler can not bowl two consecutive over in cricket

sql-server

database

check-constraints