Making Sure Every Parent Has A Child - Constraints

hello there,

I think I might know the answer to this, but I wanted to see if any one has come up with a slick idea for enforcing this relationship. If I have two tables and one is dependent on the other (parent-child relationship), how can I enforce that every parent record has a corresponding child record? Here is a code example


USE tempdb

GO

CREATE TABLE dbo.Parent
(
ParentId int NOT NULL
)

ALTER TABLE dbo.Parent ADD CONSTRAINT PK_Parent PRIMARY KEY CLUSTERED (ParentId)


CREATE TABLE dbo.Child
(
ParentId int NOT NULL
,ChildId int NOT NULL
)

ALTER TABLE dbo.Child ADD CONSTRAINT PK_Child PRIMARY KEY CLUSTERED (ParentId, ChildId)

ALTER TABLE dbo.Child ADD CONSTRAINT FK_Child_Parent FOREIGN KEY (ParentId)
REFERENCES dbo.Parent(ParentId)

INSERT INTO dbo.Parent VALUES (1)
INSERT INTO dbo.Child VALUES (1,1)
INSERT INTO dbo.Parent VALUES (2)
INSERT INTO dbo.Child VALUES (2,2)
INSERT INTO dbo.Child VALUES (2,1)
INSERT INTO dbo.Parent VALUES (3)


SELECT
p.ParentId, 'I SHOULD HAVE A DEPENDENT RECORD'
FROM
dbo.Parent p
LEFT JOIN
dbo.Child c
ON
p.ParentId = c.ParentId
WHERE c.ParentId IS NULL



ParentId 3 should have a child record associated with it. I am assuming that these are my choices:

1) code all inserts to the parent table along with a insert to the child table and wrap those in a transaction

2) place a trigger for insert on the parent table that ensures that the child table is populated after data for the parent.

Here is the gotcha, we will be using a middle-tier data access layer (nhibernate or dlink) so .NET application developers will be creating the data modifications at the transactional level. Also there might be several ongoing ETLs that populate this schema as well, so multiple points of entry and seperate code blocks. I don't want to hide business logic within triggers.

I assume that all our coders are competent and could enforce this properly via code, but I know that mistakes happen. Has any one come across this situation and have a solution for enforcing the integrity of the schema with constraints?