All Oracle errors
ORA-00001sql

Unique constraint violated

ORA-00001: unique constraint (OWNER.CONSTRAINT_NAME) violated

Why it happens

An INSERT or UPDATE tried to store a value that already exists in a column protected by a UNIQUE or PRIMARY KEY constraint.

How to fix it

Query the table for the duplicate value and remove or update it, drop the constraint if it is wrong, or use MERGE / INSERT ALL WITHOUT the unique key so the row is reused.

A note on ORA-00001

This entry is part of a hand-curated set of ORA-, FRM-, REP- and TNS- codes that actually turn up in production Oracle estates — SQL*Plus, APEX, 19c/21c, ODP.NET apps, Oracle Forms 6i/12c and Reports included. The message text above is the canonical wording; the cause and fix are written in plain language so a developer or DBA can act without digging through pages of Oracle reference docs first.

Codes outside this list of 44 are far less common. If you hit one, the official Oracle error reference and your instance's alert or listener log remain the authoritative source.

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