T-SQL INSERT-当其他列重复时的增量值

Question

I have the following table:

CREATE TABLE Budget (
Year Int,
Region varchar(50),
Amount float,
DraftNo int);

GO

INSERT INTO Budget 
VALUES
(2018, 'Region1', 500000, 1),
(2018, 'Region2', 400000, 1),
(2018, 'Region3', 300000, 1);

End users will submit data for Year, Region, and Amount through an Excel form, which will use VBA to write INSERT statements against the table. DraftNo will be 1 by default, but if there is already a match in the table on the first two columns (Year and Region), I want to increment DraftNo by one each time.

For example, if the application tries to write:

INSERT INTO Budget VALUES (2018, 'Region1', 600000, 1)

It should be converted to:

INSERT INTO Budget VALUES (2018, 'Region1', 600000, 2)

Of course, the solution will also need to recognize the max draft number for the Year/Region combination and increment one more from there, rather than always using 2.

Answer 1

If you need to add new record with incremental DraftNo:

declare @y int = 2018, @r varchar(50) = 'Region6', @a float = 3

INSERT INTO Budget VALUES (@y, @r, @a, isnull((select max(DraftNo) from Budget where [Year] = @y and Region = @r), 0) + 1)

If you need update existing records and add DraftNo:

Using MERGE :

merge Budget as trg
using (select 2018, 'Region1', 600000) as src (y, r, a)
on trg.[Year] = src.y and trg.[Region] = src.r and trg.Amount = src.a
when matched then
    update set DraftNo = DraftNo + 1
when not matched then
    insert ([Year], Region, Amount, DraftNo)
    values (y, r, a, 1);

Using Update + Insert :

declare @y int = 2018, @r varchar(50) = 'Region6', @a float = 3

update Budget 
set DraftNo = DraftNo + 1
where [Year] = @y and [Region] = @r and Amount = @a

if @@ROWCOUNT = 0
    insert Budget (Year, Region, Amount, DraftNo)
    values (@y, @r, @a, 1)