MyBatis ResultMap Guide & Examples

In MyBatis, ResultMap is an object used to map query result sets. It describes how to map database query columns to Java object properties.

ResultMap can be defined through XML configuration or annotations. When using XML configuration, you can specify the ResultMap in SQL statements using elements like ``, ``, and so on. For example:
“`xml






“`

The above code defines a ResultMap named “userMap”, which maps the “user_id” column of the query result to the “id” property of the User object, and so on. When using ResultMap in SQL statements, you can specify the ResultMap ID using the `resultMap` attribute. For example:
“`xml

SELECT * FROM users WHERE user_id = #{id}

“`

When defining ResultMap with annotations, you can use `@Results` and `@Result` annotations to specify the ResultMap. For example:
“`java
@Results(id = “userMap”, value = {
@Result(property = “id”, column = “user_id”),
@Result(property = “username”, column = “username”),
@Result(property = “password”, column = “password”),
@Result(property = “email”, column = “email”)
})
“`

The advantage of using ResultMap is that it allows mapping complex query results to object properties, providing flexibility and maintainability. Additionally, ResultMap can handle complex result set mappings like one-to-one, one-to-many, nested queries, etc.