SQL 游标生成唯一的非顺序 PINS

Question

我正在尝试为一群新员工生成非连续的唯一 PIN。 以下是它的工作原理：

1. 游标应该从表 B 中获取所有新员工
2. 为每位新员工生成新的独特别针
3. 检查新生成的PIN是否已经存在于表A中
4. 如果是，请重复第 2 步，直到我们为所有新员工获得唯一的 PIN 码
5. 将新员工编号和 PIN 码插入表 A

在表 A 上，字段为 PIN、Employee_Number、Date

我尝试使用 cursor 一个一个地插入每个新的 emp 和他的 PIN，以便在每次插入时检查唯一性：

这只会循环一次并停止，有人可以告诉我我错过了什么

 DECLARE 
    @EmpNo             VARCHAR(50), 
    @Pin               INT, 
    @today             DATETIME,
    @Upper             INT,
    @Lower             INT,
SET @Lower = 100000 ---- The lowest random number allowed
SET @Upper = 999999 ---- The highest random number allowed

DECLARE cur CURSOR FOR 

SELECT   
       Employee_Number, 
       (ROUND(((@Upper - @Lower -1) * RAND() + @Lower), 0))as PIN, 
       GETDATE()
FROM     TableB 
WHERE    Employee_Number NOT IN (SELECT Employee_Number FROM TableA)


OPEN cur
FETCH NEXT FROM cur INTO @EmpNo, @Pin, @Today

WHILE @@FETCH_STATUS=0

BEGIN    

         INSERT INTO TableA (PIN, Employee_Number, Date)
         SELECT @Pin, @EmpNo, @Today


FETCH NEXT FROM cur INTO @Pin, @EmpNo, @Today
END

CLOSE cur
DEALLOCATE cur

Answer 1

你不需要光标。另外最好使用 newid() 来生成随机数，而不是 rand()

INSERT INTO TableA (PIN, Employee_Number, Date)
SELECT pin = @Lower 
           + (   abs(convert(bigint,convert(varbinary(20),newid()))) 
               % (@Upper - @Lower + 1) 
             ),
       Employee_Number,
       GETDATE()
FROM   TableB 
WHERE  Employee_Number NOT IN (SELECT Employee_Number FROM TableA)

编辑：

要处理唯一的 pin，不使用光标的解决方案是保留所有可能 pin 的表。

create table pin
(
    pin         int primary key,
    is_used     bit default 0
)

您使用递归 cte 生成 pin

; with num as
(
    -- anchor member
    select  pin = @Lower

    union all

    -- recursive member
    select  pin = pin + 1
    from    num
    where   pin < @Upper
)
insert into pin (pin) 
select  pin
from    num

那么当您需要将 pin 分配给员工时

; with emp as
(
    select  Employee_Number, rn = row_number() over (order by Employee_Number)
    from    TableA a
    where   not exists
            (
                select  *
                from    TableB b
                where   b.Employee_Number   = a.Employee_Number
            )
),
pin as
(
    -- get unused pin, order it randomly using newid()
    select  pin, rn = row_number() over (order by newid())
    from    pin
    where   is_used = 0
)
insert into #TableB (Employee_Number, pin)
select  e.Employee_Number, p.pin
from    emp e
        inner join pin p    on  e.rn    = p.rn

在 pin 表中更新 is_used 列之后

update  p
set     is_used = 1
from    TableB b
        inner join #pin p   on  b.pin   = p.pin
where   p.is_used   = 0

Answer 2

另一种方法可能如下。

注意@EmpTable 是一个示范性的 EmpTable（为您的环境删除 @）

1) cte0 生成一个 10 行的基本计数表

2) cteR 将 cte0 扩展为 1000 行并添加一个随机字符串 (NewID())

3) cteI 将 cteR 转换为 INT（不超过 6 位）

4) 更新适用于所有 NULL PINS

Declare @EmpTable table (Employee_Number int,PIN int)
Insert Into @EmpTable values
(1,100288),(2,651701),(3,823700),
(4,NULL),(5,NULL)

Declare @Lower int=100000,@Upper int = 999999

 ;with cte0(N)   As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N))
     , cteR(R)   As (Select Distinct R=cast(NewID() as varchar(50)) From cte0 N1, cte0 N2, cte0 N3, cte0 N4) 
     , cteI(R,N) As (Select Distinct R,cast(Left(cast(abs(cast(Hashbytes('MD5',R) as int)) as varchar(25)),6) as int) From cteR R) 
Update @EmpTable Set PIN = B.N
 From  @EmpTable A
 Join  (
         Select RowNr=(Select min(Employee_Number)-1 From @EmpTable Where PIN is NULL)+Row_Number() over (Order By R)
               ,N 
          From  cteI 
          Where N Between @Lower and @Upper
            and N not in (Select Distinct PIN From @EmpTable Where PIN is not NULL)
        ) B on A.Employee_Number=B.RowNr and PIN is null


Select * from @EmpTable

更新了 EmpTable

Employee_Number PIN
1               100288   -- Same as Original
2               651701   -- Same as Original
3               823700   -- Same as Original
4               118844   -- New Random PIN
5               677855   -- New Random PIN