To find missing or gap ID numbers in an Oracle table

 To find missing or gap ID numbers in an Oracle table, you can use a query that generates a sequence of numbers and then compares it to the existing IDs in your table.

Here's a common approach using a CONNECT BY clause to generate a series of numbers:

SELECT

    (SELECT MIN(id_column) FROM your_table) + LEVEL - 1 AS missing_id

FROM

    DUAL

CONNECT BY

    LEVEL <= (SELECT MAX(id_column) FROM your_table) - (SELECT MIN(id_column) FROM your_table) + 1

MINUS

SELECT

    id_column

FROM

    your_table;