T-SQL SELECT TOP值和增量

Question

I'm currently working on a stored procedure in SQL Server 2012. I have the following table:

Id | SalesAreaId | CollectionId 
---+-------------+-----------
1  |     12      |     1
2  |     7       |     1
3  |     5       |     1

I want to select the highest CollectionId and increment it +1.

DECLARE @CollectionId INT = 1;

SELECT TOP 1 @CollectionId = [CollectionId]
FROM [MyProject].[Sales]
WHERE [CollectionId] = MAX([CollectionId])

@CollectionId = @CollectionId + 1

As a result the next @CollectionId should be 2, unfortunately this doesn't really work...

Do you have an idea on how to solve this issue?

Thank you very much!

Answer 1

Just write this as:

SELECT @CollectionId = MAX([CollectionId])
FROM [MyProject].[Sales];

Normally, you would do the increment in the SELECT and take into account an empty table:

SELECT @CollectionId = COALESCE(1 + MAX([CollectionId], 1)
FROM [MyProject].[Sales];

Answer 2

DECLARE @CollectionId INT = 1;
SELECT @CollectionId  = ((SELECT MAX(CollectionId) FROM [MyProject].[Sales])+1);    

increments the last collectionid with one if the last collectionid is the largest of all collectionids

Answer 3

You can SELECT simply as follows

SELECT TOP 1 (CollectionId + 1)
FROM Sales
ORDER BY CollectionId DESC