Executing SQL in MyBatis: Complete Guide

2 years ago
Isabella Edwards
2 minutes

In MyBatis, executing SQL statements can be achieved using Mapper interfaces and mapping files. Here are the general steps:

1. Create a Mapper interface: Define the SQL statements to be executed in the Mapper interface, such as queries, updates, deletions, and other operations.

public interface UserMapper {
    User getUserById(Long id);
}

2. Create a mapping file (XML file): Configure the mapping relationship between SQL statements and Mapper interface methods in the mapping file.

<!-- UserMapper.xml -->
<mapper namespace="com.example.mapper.UserMapper">
    <select id="getUserById" resultType="User">
        SELECT * FROM user WHERE id = #{id}
    </select>
</mapper>

3. Configure MyBatis by setting up the configuration file, where you can configure the data source and mapping files.

<!-- mybatis-config.xml -->
<configuration>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mydb"/>
                <property name="username" value="root"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/example/mapper/UserMapper.xml"/>
    </mappers>
</configuration>

Get the SqlSession object and execute SQL statements: Obtain the SqlSession object in the code, then execute SQL statements through the methods of the Mapper interface.

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
SqlSession sqlSession = sqlSessionFactory.openSession();

UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
User user = userMapper.getUserById(1L);

sqlSession.close();

By following these steps, you can execute SQL statements in MyBatis and retrieve the results. MyBatis automatically maps the results to the specified Java objects, simplifying the process of data manipulation.

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