1404
MySQLwarningddlhigh confidence
Converting column to character set
Production Risk
Low — warning only; data is converted in place.
What this means
MySQL automatically converted a column to the new character set during an ALTER TABLE CONVERT TO CHARACTER SET operation.
Why it happens
- 1ALTER TABLE ... CONVERT TO CHARACTER SET triggered an implicit column character set change
How to reproduce
trigger — this will error
trigger — this will error
ALTER TABLE t CONVERT TO CHARACTER SET utf8mb4;
expected output
Warning 1404: Converting column 'name' from latin1 to utf8mb4
Fix
Review column definitions after conversion
Review column definitions after conversion
SHOW CREATE TABLE t;
Why this works
Confirms the column character sets after the ALTER.
What not to do
✕
Sources
Official documentation ↗
MySQL 8.0 — 1404 ER_AUTO_CONVERT
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