Inserting into multiple tables using SCOPE_IDENTITY

Question

I have the following SQL code used to insert a new record into my database

DECLARE @CustomerID INT
DECLARE @PropertyID INT

BEGIN TRAN T1
    INSERT INTO c_customer (title, f_name, l_name, tel1, tel2, tel3, email, email2, 
                            type, primary_contact, tel1type, tel2type, tel3type) 
    VALUES(@title, @fname, @lname, @tel1, @tel2, @tel3, @email, @email2, 
           'Owner', 1, @teltype1, @teltype2, @teltype3)

    SET @CustomerID = SCOPE_IDENTITY()

    BEGIN TRAN T2
        INSERT INTO c_property (address1, address2, address3, post_code, city, county) 
        VALUES (@address1, @address2, @address3, @postcode, @city, @county)

        SET @PropertyID = SCOPE_IDENTITY()

        UPDATE c_property 
        SET invoice_flag = @PropertyID
        WHERE c_property = @PropertyID

        BEGIN TRAN T3

            INSERT INTO c_customer_assignment 
            VALUES (@PropertyID, @CustomerID)

            COMMIT TRAN T1
            COMMIT TRAN T2
            COMMIT TRAN T3

    SELECT @CustomerID, @PropertyID

This code works as I want it to, making sure that the added details are linked correctly using the c_customer_assignment table, however it does look overly complicated and I was wondering if I had taken the right approach to solving the problem (Not sure if I even need the nested transactions at all).

I know at least one transaction is needed, as I do need to make sure records don't get mismatched due to other users inserting at the same time.

Do I also need to review transaction isolation too, or is this enough?

Answer 1

You just need one transaction:

DECLARE @CustomerID INT
DECLARE @PropertyID INT

BEGIN TRAN T1

    INSERT INTO c_customer (title, f_name, l_name, tel1, tel2, tel3, email, email2, type, primary_contact, tel1type, tel2type, tel3type) 
    VALUES(@title, @fname, @lname, @tel1, @tel2, @tel3, @email, @email2, 'Owner', 1, @teltype1, @teltype2, @teltype3)

    SET @CustomerID = SCOPE_IDENTITY()

    INSERT INTO c_property (address1, address2, address3, post_code, city, county) 
    VALUES (@address1, @address2, @address3, @postcode, @city, @county)

    SET @PropertyID = SCOPE_IDENTITY()

    UPDATE c_property 
    SET invoice_flag = @PropertyID
    WHERE c_property = @PropertyID

    INSERT INTO c_customer_assignment 
    VALUES (@PropertyID, @CustomerID)

    COMMIT TRAN T1

    SELECT @CustomerID, @PropertyID