如何插入使用顺序GUID作为主键的表？

Question

这是我正在查看的表的简化版本:

CREATE TABLE [dbo].[FrustratingTable]
(
    [Id] Uniqueidentifier NOT NULL
    , [SecondField] [datetime]
    , [ThirdField] varchar(128)
)

我想在此表中插入新记录.我尝试了3种方法:

INSERT INTO [dbo].[FrustratingTable] (Id, SecondField, ThirdField)
    SELECT newid() as Id, 
           '6/25/2015' as SecondField, 'Example' as ThirdField

这种方法插入,但结果键不是一个很好的顺序GUID,就像表中的其他键

INSERT INTO [dbo].[FrustratingTable] (Id, SecondField, ThirdField)
SELECT NEWSEQUENTIALID() as Id, '6/25/2015' as SecondField, 'Example' as ThirdField

这失败了,错误

newsequentialid()内置函数只能在CREATE TABLE或ALTER TABLE语句中的"uniqueidentifier"类型的列的DEFAULT表达式中使用.它不能与其他运算符组合以形成复杂的标量表达式.

INSERT INTO [dbo].[FrustratingTable] (SecondField,ThirdField)
SELECT '6/25/2015' as SecondField, 'Example' as ThirdField

这失败了,错误

无法将值NULL插入列'id',表'mydatabase.dbo.frustratingtable'; 列不允许空值.INSERT失败.

是否有可能在不改变表定义的情况下解决这个问题？

Answer 1

您可以通过使用表变量来执行此操作:

declare @t table (
    ID uniqueidentifier not null default newsequentialid(),
    SecondField datetime,
    ThirdField varchar(128)
)
insert into @t (SecondField,ThirdField)
    output inserted.ID,inserted.SecondField,inserted.ThirdField
    into FrustratingTable
values
('20150101','abc'),
('20150201','def'),
('20150301','ghi')

select * from FrustratingTable

结果:

Id                                   SecondField             ThirdField
------------------------------------ ----------------------- ------------
1FEBA239-091C-E511-9B2F-78ACC0C2596E 2015-01-01 00:00:00.000 abc
20EBA239-091C-E511-9B2F-78ACC0C2596E 2015-02-01 00:00:00.000 def
21EBA239-091C-E511-9B2F-78ACC0C2596E 2015-03-01 00:00:00.000 ghi

由于表变量通过a设置值default,我们可以使用NEWSEQUENTIALID().

当然,对于非常大的数据集,暂时存在两个潜伏的数据副本会受到惩罚.

另一种方法是使用一种名为COMB的旧解决方案,它在之前使用过NEWSEQUENTIALID():

SELECT CAST(CAST(NEWID() AS BINARY(10)) + CAST(GETDATE() AS BINARY(6)) AS UNIQUEIDENTIFIER)

产生uniqueidentifiers比NEWID()本身更好的局部性.