When One Row Maps to Many

What They're Really Testing The interviewer is testing three things in sequence. First: do you recognize that this is a many-to-many problem that cannot be solved by adding a foreign key to the fact table? Second: do you know that a naive junction table will inflate aggregates? Third: do you know about weighting factors? Most candidates clear the first gate. Far fewer clear all three. The Problem in Three Sentences State the problem in one sentence: 'A $1,000 sale attributed to 3 sales reps becomes $3,000 in the SUM. The join inflated it 3x.' Open with this. The interviewer immediately knows you understand the many-to-many aggregation problem. Then say: 'That is why we need a bridge table with weights that sum to 1.0 per order.' $3,000 This is the single example you need in an interview. S