死锁SQL Server使用表的最大值

Question

I have the following situation in sql server. I have two tables ( companies and orders ). Within orders there is the companyid . I need a complex identity or sequence, to identify the next order number relating to the company.

Ex: Companies

ID - Name
1 - Microsoft
2 - Google

Orders

ID - Description - Number - CompanyID
1  - Name        - 1      - 1
2  - Name        - 2      - 1
3  - Name        - 1      - 2
4  - Name        - 2      - 2

The problem is the number. It needs to be an incremental according to the company. What is the best solution?

I ask this, because I'm running the insertion of several requests in parallel and I'm having a deadlock in sql server. I request the last Number using Max of Orders, but how is parallel, iam having a deadlock. What would be the best solution?

Thanks.

Answer 1

I believe that several SEQUENCE objects could help you.

"Unlike identity column values, which are generated when rows are inserted, an application can obtain the next sequence number before inserting the row by calling the NEXT VALUE FOR function."

But there is a caveat: "The sequence number is allocated when NEXT VALUE FOR is called even if the number is never inserted into a table." This means that you cannot guarantee the consecutiveness of the values - and to be honest I don't think that you can ever guarantee such a feature, not without using complex logic.