Resolving Hibernate QuerySyntaxException: 'users' Not Mapped

Why do I encounter org.hibernate.hql.internal.ast.QuerySyntaxException when trying to retrieve users from the database?

The error you are encountering, `QuerySyntaxException: users is not mapped`, is typically related to misconfigurations in your Hibernate mappings or incorrect HQL queries.

// Corrected code snippet for fetching users
List<User> result = (List<User>) session.createQuery("from User").list();

Causes

• The entity class is not correctly mapped to the table name in the database.
• The table name in the HQL query does not match the corresponding entity class name or its mapping.
• Using an incorrect case for identifiers. Hibernate is case-sensitive when it comes to entity names.

Solutions

• Change the HQL query from `from users` to `from User`, as HQL queries should refer to the entity class name rather than the database table name.
• Ensure that the entity class is mapped properly in your Hibernate configuration files.
• If your table name is indeed `Users` (with an uppercase U), and your entity class is `User`, ensure you refer to it as 'User' in your query.

Mistake: Referencing the table name instead of the entity class name in HQL.

Solution: Use the entity class name when writing HQL queries.

Mistake: Not matching the case of class names and table names, leading to confusion.

Solution: Always be consistent with naming conventions and follow Java class naming standards in HQL.