Spring DataIntegrityViolationException: 'line_id' Field Missing Default Value - Troubleshooting Guide

This exception is thrown when there is a data integrity violation in the database. In this case, the error is caused by a SQL exception stating that the 'line_id' field does not have a default value.

The error is most likely occurring in the LineDao class in the add method. The error occurs while setting the parameters for the SQL insert statement. The SQL statement is trying to insert values into the 'line' table, but the 'line_id' field does not have a default value specified.

To fix this issue, you need to either provide a default value for the 'line_id' field in the database table or update your code to provide a value for the 'line_id' field when inserting a new record into the 'line' table.