Answer
A sequence is a database object that generates a sequence of numeric values. • It is commonly used to supply surrogate identifiers. • Calling a sequence advances it independently of ordinary table row visibility. • Gaps can occur and sequence values should not be treated as gapless business numbering.
💡 SQL Example
CREATE SEQUENCE order_number_seq START WITH 1000;
SELECT nextval('order_number_seq');
Result
1000
⚡ Quick Revision
A sequence generates numeric values and may contain gaps.