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| 1 | +This SQL code aims to identify gaps in sequential data from an orders table. First, it creates a temporary table called "Sequences" that holds the minimum and maximum order numbers from the orders table. Then, it selects the missing sequence numbers by adding 1 to the minimum order number. It uses the "NOT EXISTS" clause to check if the next order number after the minimum doesn't exist in the orders table. This approach helps identify any gaps in the sequence of order numbers in the orders table. |
| 2 | + |
| 3 | +```sql |
| 4 | +-- Create a temporary table to hold the sequence information |
| 5 | +WITH Sequences AS ( |
| 6 | + -- Select the minimum and maximum order numbers to define the range |
| 7 | + SELECT MIN(order_number) AS start_seq, MAX(order_number) AS end_seq |
| 8 | + FROM orders |
| 9 | +) |
| 10 | +-- Select the missing sequence numbers |
| 11 | +SELECT start_seq + 1 AS missing_sequence |
| 12 | +-- Check if there is no order number exists in the sequence |
| 13 | +FROM Sequences |
| 14 | +WHERE NOT EXISTS ( |
| 15 | + -- Check if the next order number exists in the orders table |
| 16 | + SELECT 1 |
| 17 | + FROM orders o |
| 18 | + WHERE o.order_number = Sequences.start_seq + 1 |
| 19 | +) |
| 20 | + |
| 21 | +``` |
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