3108
MariaDBERRORNotableSchemaHIGH confidence
Column is used by a generated column and cannot be dropped
Production Risk
Low — DDL fails; no columns are dropped.
What this means
An attempt was made to drop a column that is referenced by a generated column expression.
Why it happens
- 1ALTER TABLE DROP COLUMN on a column that is a base column for a generated column.
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t DROP COLUMN raw; -- raw is used in generated column gen
expected output
ERROR 3108 (HY000): Column 'raw' has a generated column dependency.
Fix
Drop the generated column before dropping its base column
Drop the generated column before dropping its base column
ALTER TABLE t DROP COLUMN gen, DROP COLUMN raw;
Why this works
Removing the dependent generated column first eliminates the dependency.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 3108 ER_DEPENDENT_BY_GENERATED_COLUMN2
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