Spring DataIntegrityViolationException: 'Field 'line_id' doesn't have a default value'

This error is caused by a 'DataIntegrityViolationException' in the 'LineDao' class of a Spring application. The exception message suggests that there is a problem with updating the database due to a 'SQLException' with the message 'Field 'line_id' doesn't have a default value'.

Based on the provided information, it appears that the 'line_id' field in the database table is not set to have a default value, and when trying to insert a new record into the 'line' table, the 'line_id' field is not provided with a value.

To fix this issue, you have a few options:

Set a default value for the 'line_id' field in the database table. This will ensure that if a value is not provided during the insert operation, a default value will be used instead.
Modify the insert statement to provide a value for the 'line_id' field. This can be done by either explicitly specifying a value or using a generated value, such as an auto-incrementing primary key.
Check if there is any code in the 'LineDao' class that is responsible for setting the 'line_id' field before executing the insert statement. Ensure that this code is functioning correctly and providing a valid value for the 'line_id' field.

Once you have resolved the issue with the 'line_id' field, the 'DataIntegrityViolationException' should no longer occur.