Update followed by insert in a stored procedure - sql

Question

I'm not sure that's the correct way making an update followed by insert in a stored procedure.
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[io_sp_admin_add_emp]
#id BIGINT,
#lastName VARCHAR(20),
#firstName VARCHAR(20)
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRY
BEGIN TRANSACTION [TranAddEmp]
DECLARE #identity BIGINT = 0
INSERT INTO empTable(LastName, FirstName, hash_id)
VALUES (#lastName, #firstName,
HashBytes('SHA2_256', CAST(#id AS VARBINARY(50))))
SELECT #identity = ##identity
UPDATE empTable
SET rowId = incId -- both are columns in empTable
WHERE hash_id = #identity
COMMIT TRANSACTION [TranAddEmp]
END TRY
BEGIN CATCH
ROLLBACK TRANSACTION [TranAddEmp]
END CATCH
END

Answer 1

A simple change to your current code can give you what you're looking for.
Instead of messing around with ##Identity, which is almost never the right thing to do, you compute the hash of the #Id value once, store it in a local variable, and use it for both the insert statement and the where clause of the update statement - That is, assuming the HashId column is unique.
That being said, I'm not sure why you need the rowId column as well as the incId column - unless one of them is designed to change it's value through an update statement in the lifetime of the row - you are simply keeping redundant data.
Here's an improved version of your stored procedure:
CRETAE PROCEDURE [dbo].[io_sp_admin_add_emp]
#id BIGINT,
#lastName varchar(20),
#firstName varchar(20)
AS
BEGIN
SET NOCOUNT ON;
BEGIN TRY
BEGIN TRANSACTION [TranAddEmp]
-- Compute the hash once, store in a local variable
DECLARE #HashId varbinary(8000) = HashBytes('SHA2_256', cast(#id as varbinary(50)))
INSERT INTO empTable(
LastName,
FirstName,
hash_id
)
VALUES(
#lastName,
#firstName,
#HashId
)
UPDATE empTable
SET rowId = incId
WHERE hash_id = #HashId
COMMIT TRANSACTION [TranAddEmp]
END TRY
BEGIN CATCH
-- make sure transaction has started and is not commited
IF ##TRANCOUNT > 0
ROLLBACK TRANSACTION [TranAddEmp]
END CATCH
END

Answer 2

There is a great keyword OUTPUT. As MSDN says:
Returns information from, or expressions based on, each row affected
by an INSERT, UPDATE, DELETE, or MERGE statement. These results can be
returned to the processing application for use in such things as
confirmation messages, archiving, and other such application
requirements. The results can also be inserted into a table or table
variable. Additionally, you can capture the results of an OUTPUT
clause in a nested INSERT, UPDATE, DELETE, or MERGE statement, and
insert those results into a target table or view.
You can insert your inserted id's into table through OUTPUT keyword. For example:
DECLARE #InsertedIDs TABLE (ID varbinary(8000))
INSERT INTO empTable(
LastName,
FirstName,
hash_id
)
OUTPUT HashBytes('SHA2_256', cast(INSERTED.ID as varbinary(50))) INTO #InsertedIDs(ID)
VALUES(
#lastName,
#firstName,
HashBytes('SHA2_256', cast(#id as varbinary(50)))
)
UPDATE empTable
Set rowId = incId -- both are columns in empTable
WHERE hash_id in (SELECT ID IN #InsertedIDs)