One way to generate contiguous TrackingNumber is using SELECT MAX(TrackingNumber) +1 computation. This method (used before IDENTITY/SEQUENCE was invented) is processing intensive and can cause blocking or even deadlocks.
Is there a better way? Thanks.
CREATE TABLE Tracking(
ID BIGINT IDENTITY(1,1) PRIMARY KEY,
TrackingID [uniqueidentifier] NOT NULL UNIQUE,
TrackingNumber [bigint] NOT NULL UNIQUE,
TrackingAsset [uniqueidentifier] NOT NULL UNIQUE,
ModifiedDate datetime2 default (sysdatetime())
);
INSERT Tracking(TrackingID, TrackingNumber, TrackingAsset) VALUES (NEWID(), 1, NEWID());
GO
INSERT Tracking(TrackingID, TrackingNumber, TrackingAsset)
VALUES (NEWID(), (SELECT MAX(TrackingNumber)+1 FROM Tracking), NEWID());
GO 9
SELECT * FROM Tracking ORDER BY TrackingNumber;
/*
ID TrackingID TrackingNumber TrackingAsset ModifiedDate
1 0C799924-A820-45C4-9F8D-495F501A2F7C 1 AD8744AD-B055-481B-84BC-1F20750B1337 2014-02-18 08:53:49.9136069
2 DC58CB6B-7BFC-42D6-A670-01CF6F88C887 2 264167F5-044E-48EF-9A67-26C2D62E0705 2014-02-18 08:55:11.9212975
3 3716F937-92C3-40DF-9369-9E4B8B646F62 3 B277F6E9-C5E2-4FEF-A648-8D6BF4D4077D 2014-02-18 08:55:11.9362984
4 B1BBB174-D9A3-45D5-8E1E-D3D9DC539C85 4 8832DC7A-AD22-4F50-80D0-619A29CAB341 2014-02-18 08:55:11.9382985
5 4150235D-565B-4EEC-8F3D-A029A74E020F 5 C48B5998-AEB5-444F-A783-309B6215277A 2014-02-18 08:55:11.9392985
6 0D690CBB-A1FF-412E-AF33-FF50F394BA57 6 F1F88C67-3105-4204-810D-0D3C3E9A7F3C 2014-02-18 08:55:11.9412986
7 1E02C4C3-0B52-44F6-804E-F063C558094F 7 71301EC3-7C88-476A-BDF2-FFD96F470452 2014-02-18 08:55:11.9422987
8 53561890-1DEA-4518-B78A-F238F76E77D9 8 1BBFDEA5-7233-41E6-9741-205998223D10 2014-02-18 08:55:11.9432988
9 19E27235-E1EC-4E13-92D4-16A7BD7C51F6 9 4D860003-4D6C-4C62-9302-5BE5E65A2ED8 2014-02-18 08:55:11.9442988
10 E0382932-2FC1-4408-B318-782C741ECA26 10 E4BE5CBB-25AE-4270-AE57-8ECB7E1B0F68 2014-02-18 08:55:11.9452989
*/Kalman Toth Database & OLAP Architect SELECT Video Tutorials 4 Hours
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