EC
1971
MySQLERRORCommonDDLHIGH confidence

Column has duplicated value in SET/ENUM definition

Production Risk

None — DDL is rejected.

What this means

An ENUM or SET column definition lists the same value more than once. Each member value in ENUM and SET must be unique.

Why it happens
  1. 1ENUM('a', 'b', 'a') — 'a' appears twice.
  2. 2SET('read', 'write', 'read') — 'read' appears twice.
How to reproduce
trigger — this will error
trigger — this will error
CREATE TABLE t (status ENUM('active', 'inactive', 'active'));

expected output

ERROR 1971 (HY000): Column 'status' has duplicated value 'active' in ENUM.

Fix

Remove duplicate values from the ENUM or SET definition

Remove duplicate values from the ENUM or SET definition
CREATE TABLE t (status ENUM('active', 'inactive', 'pending'));

Why this works

Each value in an ENUM or SET must be unique.

Sources
Official documentation ↗

MySQL 8.0 — 1971 ER_DUPLICATED_VALUE_IN_TYPE

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