INSERT or UPDATE fails because the supplied value exceeds the column’s defined length or data type limit.
“Data too long for column” appears when a value is longer than the column’s declared size. Trim, cast, or enlarge the column (ALTER TABLE … MODIFY) to resolve the failure.
ERROR 1406 (22001): Data too long for column 'title' at row 1
MySQL throws error 1406 when an INSERT or UPDATE tries to write a value whose length exceeds the column’s defined size or data-type limit. The server refuses the change, preserving data integrity.
The error surfaces most in VARCHAR, CHAR, TEXT, BLOB, ENUM, and numeric fields with strict mode enabled.
Ignoring it risks silent truncation or application crashes, so fixing it quickly is essential.
Oversized string literals, concatenated variables, or improperly cast numbers commonly exceed column length limits.
Strict SQL mode converts these overflows into hard errors.
Mismatched character sets or collations inflate byte length, letting multibyte UTF-8 characters overflow a column sized for single-byte encodings.
ETL jobs and ORMs that auto-map wide source fields to narrow target columns also trigger the error.
First, identify the offending column and row, then decide to resize the schema, trim the data, or cast it.
Always test changes in staging.
Use ALTER TABLE to enlarge the column, or apply SUBSTRING(), LEFT(), or CAST() in the query to fit existing width.
Form inputs longer than VARCHAR(255) cause web-app failures; resize to VARCHAR(512) or TEXT.
Decimal values with excessive precision overflow DECIMAL(10,2); adjust to DECIMAL(14,4) or ROUND() the value.
JSON dumps serialized into a VARCHAR column quickly exceed limits; switch to JSON or LONGTEXT types to accommodate larger payloads.
Validate and truncate user input at the application layer.
Keep database schema in sync with changing business requirements through migrations.
Adopt Galaxy’s AI copilot to inspect column metadata inline, preventing accidental overflows while you type SQL.
SQL Server’s “String or binary data would be truncated” and PostgreSQL’s “value too long for type character varying” are analogous; solutions mirror the MySQL fixes—resize columns or trim input.
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MySQL 8+ shows the column name in the error. For older versions, enable general log or insert rows individually to isolate the offending column.
It prevents the hard error but silently truncates data, risking corruption. Prefer resizing or cleaning data instead.
Only metadata changes are logged; storage grows only with actual data length. Impact on performance is minimal for moderate sizes.
Galaxy flags length mismatches while you type, suggests ALTER statements, and lets teams endorse the final fix for reuse.
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