IGNORE option tells the server to ignore some common errors.
IGNORE can be used with the following statements:
- INSERT (see also INSERT IGNORE)
- LOAD DATA INFILE
- ALTER TABLE
- CREATE TABLE ... SELECT
- INSERT ... SELECT
The logic used:
- Variables out of ranges are replaced with the maximum/minimum value.
NOT NULLfield will insert 0 ( in a numerical field), 0000-00-00 ( in a date field) or an empty string ( in a character field).
- Rows that cause a duplicate key error or break a foreign key constraint are not inserted, updated, or deleted.
The following errors are ignored:
|Error number||Symbolic error name||Description|
|Can't write; duplicate key in table '%s'|
|Column '%s' cannot be null|
|Duplicate entry '%s' for key %d|
|Subquery returns more than 1 row|
|Out of range value for column '%s' at row %ld|
|Data truncated for column '%s' at row %ld|
|Truncated incorrect %s value: '%s'|
|Incorrect integer value|
|Cannot delete or update a parent row|
|Cannot add or update a child row: a foreign key constraint fails (%s)|
|Table has no partition for value %s|
|Duplicate entry '%s' for key '%s'|
|Table has no partition for some existing values|
|Found a row not matching the given partition set|
Ignored errors normally generate a warning.
A property of the
IGNORE clause consists in causing transactional engines and non-transactional engines (like InnoDB and Aria) to behave the same way. For example, normally a multi-row insert which tries to violate a
UNIQUE contraint is completely rolled back on InnoDB, but might be partially executed on Aria. With the
IGNORE clause, the statement will be partially executed in both engines.
Duplicate key errors also generate warnings. The OLD_MODE server variable can be used to prevent this.