output_text.txt

Alright, given the tables have already been created, here's how you can construct an SQL INSERT query to insert a customer record, ensuring the company is stored in a different table and that the location is one of the allowed ones:

```sql
-- Insert Company or get its ID
INSERT INTO Companies (company_name)
VALUES ('Laiyer')
ON DUPLICATE KEY UPDATE company_id = LAST_INSERT_ID(company_id);

-- Insert Customer with given values and ensure the location is allowed
INSERT INTO Customers (first_name, IP, company_id, location_id)
SELECT 'John Doe', '127.0.0.1', LAST_INSERT_ID(), location_id
FROM AllowedLocations
WHERE location_name = 'New York, US';
```

Note:

1. LAST_INSERT_ID() fetches the ID of the last inserted row or the existing company's ID due to the ON DUPLICATE KEY UPDATE statement.
2. This approach relies on the assumption that the company_name column in the Companies table has a unique constraint to avoid duplicate entries.
3. The customer insert uses a SELECT statement from the AllowedLocations table to ensure that only valid/allowed locations are used for inserting the customer. If location doesn't exist in the AllowedLocations table, then no insert will occur for the customer.