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.