What is the purpose of the resulttype in MyBatis?

The purpose of resultType in Mybatis is to specify the data type of the SQL query results.

In Mybatis, when executing a query SQL statement, it is necessary to specify the data type of the query result in order for Mybatis to correctly map the query result to the corresponding Java object.

In general, resultType can be any Java data type, such as String, Integer, Long, Date, etc. Alternatively, it can also be a custom Java object where the query result is mapped to a custom Java object. In this case, we need to specify the fully qualified name of the custom object in the configuration file.

In the Mapper XML file, we can specify the data type of the query result using the resultType attribute. For example:

<select id="getUser" resultType="com.example.User">
    select * from user where id=#{id}
</select>

In the example above, by specifying resultType as com.example.User, Mybatis will map the query results to the User object.

It is important to note that if the query result has only one field, you can use resultType to specify the data type of that field. If the query result has multiple fields, you can use resultMap to specify the mapping relationship of each field.

In summary, the purpose of resultType is to specify the data type of the query result, in order to correctly map the query result to the corresponding Java object.