错误信息： Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root causejava.sql.SQLIntegrityConstraintViolationException: Column 'aaa' cannot be null at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:117) at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)数据库字段信息： `aaa` VARCHAR(255) NOT NULL DEFAULT '' COLLATE 'utf8mb4_general_ci',public class XXX { @Column(name = "`aaa`") private String aaa;}请问在数据库提供了默认值的情况下，为什么还会报 Column cannot be null 呢？