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Find a Gap in Sequence

MediumSQL · PostgreSQL00:00
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Your question is Find a Gap in Sequence. Start with the requirements and the two tables on the right.

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Problem

Write a SQL query to find a gap in a sequence of numbers.

Use sequence_ranges to define inclusive numeric ranges and sequence_values to store observed numbers. Return every number that is absent from its defined range, including ranges with no observed values.

Output

  1. One row per missing number
  2. Columns: range_id, missing_number
  3. Include missing numbers only, ordered by range_id and then missing_number ascending

Schema

sequence_ranges
ColumnTypeDescription
range_idPKINTIdentifier for a numeric sequence range
start_numberINTInclusive lower bound of the range
end_numberINTInclusive upper bound of the range
sequence_values
ColumnTypeDescription
value_idPKINTIdentifier for an observed sequence value
range_idINTReferenced sequence range
sequence_numberINTObserved integer in the sequence
Tablessequence_rangessequence_values
Your solutionPostgreSQL
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