What are the challenges you will have when you have 2 big tables, we need to join them but common column is duplicate?
Asked in the technical_round_1 stage. Using the provided tables, write a query that returns one row per non-null key, choosing the most recent record from each source. Preserve keys present in only one source.
common_key, source_a_record_id, source_a_value, source_b_record_id, source_b_valuecommon_key ascending, with NULL values for a missing source record.| Column | Type | Description |
|---|---|---|
| record_idPK | INT | Unique identifier for a source A record |
| common_key | INT | Business key used to match records |
| updated_at | TIMESTAMP | Record update timestamp |
| value | VARCHAR(100) | Value carried by the source A record |
| Column | Type | Description |
|---|---|---|
| record_idPK | INT | Unique identifier for a source B record |
| common_key | INT | Business key used to match records |
| updated_at | TIMESTAMP | Record update timestamp |
| value | VARCHAR(100) | Value carried by the source B record |