MyBatis - (一) 基本数据操作命令和简单映射

灰太狼 2022-03-29 07:52 98阅读 0赞

**1. 简单的select映射**

<mapper namespace="com.mybatis3.mappers.StudentMapper">
        <select id="findStudentById" parameterType="int" resultType="Student">
            select stud_id as studId, name, email, dob 
            from Students 
            where stud_id=#{studId}
         </select>
    </mapper>

映射接口:

package com.mybatis3.mappers;
    public interface StudentMapper
    {
     Student findStudentById(Integer id);
    }

**2. 简单的insert映射**

<insert id="insertStudent" parameterType="Student">
         INSERT INTO STUDENTS(STUD_ID,NAME,EMAIL, PHONE)
         VALUES(#{studId},#{name},#{email},#{phone})
    </insert>

映射接口:

package com.mybatis3.mappers;
    public interface StudentMapper
    {
     int insertStudent(Student student);
    }

自增主键:

useGeneratedKeys="true" keyProperty="studId"

<insert id="insertStudent" parameterType="Student" useGeneratedKeys="true" keyProperty="studId">
     INSERT INTO STUDENTS(NAME, EMAIL, PHONE)
     VALUES(#{name},#{email},#{phone})
    </insert>

**3. 简单的update映射**

<update id="updateStudent" parameterType="Student">
         UPDATE STUDENTS SET NAME=#{name}, EMAIL=#{email}, PHONE=#{phone}
         WHERE STUD_ID=#{studId}
    </update>

**4. 简单的delete映射**

<delete id="deleteStudent" parameterType="int">
         DELETE FROM STUDENTS WHERE STUD_ID=#{studId}
    </delete>

映射接口:

package com.mybatis3.mappers;
    public interface StudentMapper
    {
     int deleteStudent(int studId);
    }

**5. 简单的结果映射**

resultMap

<resultMap id="StudentResult" type="com.mybatis3.domain.Student">
        <id property="studId" column="stud_id"/>
        <result property="name" column="name"/>
        <result property="email" column="email"/>
        <result property="phone" column="phone"/>
    </resultMap>
    
    <select id="findAllStudents" resultMap="StudentResult" >
        SELECT * FROM STUDENTS
    </select>
    
    <select id="findStudentById" parameterType="int" resultMap="StudentResult">
        SELECT * FROM STUDENTS WHERE STUD_ID=#{studId}
    </select>