MyBatis | SELECT Queries | Getting a Single Result

Source code

sample_mapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="sample.mybatis">
  <select id="selectTest" resultType="map">
    select * from test_table limit 1
  </select>
</mapper>

Main.java

package sample.mybatis;

import java.io.InputStream;
import java.util.Map;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Main {

    public static void main(String[] args) throws Exception {
        try (InputStream in = Main.class.getResourceAsStream("/mybatis-config.xml")) {
            SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);

            try (SqlSession session = factory.openSession()) {
                Map<String, Object> result = session.selectOne("sample.mybatis.selectTest");
                System.out.println(result);
            }
        }
    }
}

Execution result

{id=1, value=fizz}

Explanation

  • Use the selectOne() method when the query result is a single row and you want to obtain it as one object.
  • If the query returns multiple records, TooManyResultsException is thrown.
  • If the query returns no records, null is returned.