SQL · Meta · Medium
Write a SQL query that returns the share of distinct callers in the calls table who have used both call types. Each row in calls represents one call, where sender_id identifies the caller and call_type is either 'video' or 'voice'. A caller qualifies when the same sender_id appears with at least one 'video' row and at least one 'voice' row. The denominator is the number of unique sender_id values in the entire calls table. Compute the percentage as $$100 \times…
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