Question

我有下表：

VehicleID Reg_ID Next_RegID EntryDate
330034    9111   NULL        2010-12-06 00:00:00
330034    9113   NULL        2010-12-09 00:00:00

在第一行，我需要使用第二行的Reg_ID更新Next_RegId列，其中VehicleId或（VIN / ChassisNumber）相同。最后一个条目的Next_RegID列应保持为空。

我已经创建了一个完美的while循环程序，但是表中有数百万条记录需要很长时间才能完成。因此，我想知道你们中是否有人处理过这类问题而且有解决方案。

这是我写的程序，并提前感谢您的所有帮助：

Declare @i as integer;
Declare @x as integer;
Declare @y as integer

Set @i= (Select Max(RID) from TempRegistration)
Set @x= 0
Set @y= 1
Declare @curChassis as nvarchar(100)
Declare @nextChassis as nvarchar(100)

  While (@x <= @i)
  Begin
set @curChassis = (Select ChassisNumber from TempRegistration where RID = @x)
set @nextChassis = (Select ChassisNumber from TempRegistration where RID = @y)

If (@curChassis = @nextChassis)
Begin
    Update Registration set NextRegistrationId = (Select RegistrationId from      TempRegistration where RID = @y)
    Where RegistrationId = (Select RegistrationId from TempRegistration where RID = @x)
End

Set @x = @x + 1
Set @y = @y + 1

Print(@x)
    End

TempRegistration是我创建的一个临时表，用于分配一个row_id，引导while循环将Reg_ID分配给前一行的Next_RegId。

Answer 1

这可以通过一个UPDATE查询来完成。你没有提到你的RDBMS ......

对于MSSQL：

Update Registration as t1
set NextRegistrationId = (Select TOP 1 RegistrationId 
                                       from Registration
                                       where RID = t1.RID 
                                         and EntryDate>t1.EntryDate
                                       order by EntryDate DESC)

对于MySQL

Update Registration as t1
set NextRegistrationId = (Select RegistrationId 
                                       from Registration 
                                       where RID = t1.RID 
                                          and EntryDate>t1.EntryDate
                                       order by EntryDate DESC 
                                       LIMIT 1)

如果RID随着EntryDate的增加而增加

Update Registration as t1
set NextRegistrationId = (Select MIN(RegistrationId) 
                                       from Registration 
                                       where RID = t1.RID
                                       and EntryDate>t1.EntryDate
                          )

Answer 2

经过测试，它似乎正在运行，但此版本使用CTE（SQL Server）

with RegDetails as
(
select VehicleID, Reg_ID, ROW_NUMBER() OVER(PARTITION BY VehicleID ORDER BY EntryDate) AS ROWNUMBER
FROM dbo.Vehicle)
UPDATE a SET a.Next_RegID = b.Reg_ID
FROM RegDetails b
INNER JOIN dbo.Vehicle a ON (a.VehicleID = b.VehicleID)
WHERE b.ROWNUMBER = 2 and a.Next_RegID IS NULL and a.Reg_ID != b.Reg_ID

更新Next_ID列

2 个答案: