Mybatis使用笔记（一）

前言

	<resultMap id="BaseResultMap" type="com.spring.demo.entity.Student">
        <id column="id" property="id" jdbcType="INTEGER"/>
        <result column="student_name" property="studentName" jdbcType="VARCHAR"/>
        <result column="student_sex" property="studentSex" jdbcType="VARCHAR"/>
        <result column="student_class" property="studentClass" jdbcType="INTEGER"/>
        <result column="student_age" property="studentAge" jdbcType="INTEGER"/>
    </resultMap>

    <sql id="All_Menu">
        id, student_name, student_sex, student_class, student_age
    </sql>

查询

	<!--无参数-->
    <select id="selectAll" resultMap="BaseResultMap">
        select
        <include refid="All_Menu"/>
        from student_table
    </select>

	<!--有参数-->
    <select id="selectById" resultMap="BaseResultMap" parameterType="java.lang.Integer">
        select
        <include refid="All_Menu"/>
        from student_table
        where id = #{id, jdbcType=INTEGER}
    </select>

修改

    <update id="updateById" parameterType="com.spring.demo.entity.Student">
        update student_table
        <set>
            <if test="studentName != null and studentName != ''">
                student_name = #{studentName},
            </if>
            <if test="studentSex != null and studentSex != ''">
                student_sex = #{studentSex},
            </if>
            <if test="studentClass != null and studentClass != ''">
                student_class = #{studentClass},
            </if>
            <if test="studentAge != null and studentAge != ''">
                student_age = #{studentAge},
            </if>
        </set>
        <where>
            id = #{id}
        </where>
    </update>

插入

	<!--插入一个学生信息-->
    <insert id="insertStudent" parameterType="com.spring.demo.entity.Student">
        insert into student_table
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="studentName != null and studentName != ''">
                student_name,
            </if>
            <if test="studentSex != null and studentSex != ''">
                student_sex,
            </if>
            <if test="studentClass != null and studentClass != ''">
                student_class,
            </if>
            <if test="studentAge != null and studentAge != ''">
                student_age,
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="studentName != null and studentName != ''">
                #{studentName, jdbcType=VARCHAR},
            </if>
            <if test="studentSex != null and studentSex != ''">
                #{studentSex, jdbcType=VARCHAR},
            </if>
            <if test="studentClass != null and studentClass != ''">
                #{studentClass, jdbcType=VARCHAR},
            </if>
            <if test="studentAge != null and studentAge != ''">
                #{studentAge, jdbcType=VARCHAR},
            </if>
        </trim>
    </insert>
	<!--插入一个学生信息列表-->
    <insert id="insertStudentList">
        insert into student_table (student_name, student_sex, student_class, student_age)
        values
        <foreach collection="list" item="item" separator=",">
            (#{item.studentName}, #{item.studentSex},
            #{item.studentClass}, #{item.studentAge})
        </foreach>
    </insert>

删除

    <!--通过id删除信息-->
    <delete id="deleteStudentById" parameterType="java.lang.Integer">
        delete from student_table where id = #{id}
    </delete>
    <!--传入List删除-->
    <delete id="deleteByIdList" parameterType="java.util.List">
        delete from student_table
        where id in (
        <foreach collection="list" item="id" index="index" separator=",">
            #{id}
        </foreach>
        )
    </delete>

其它

resultType和resultMap的区别：

resultType是简单的返回类型，比如查询数据只需要一个简单的String、int只需要使用resultType即可满足需求，
resultMap是resultType的高级版，可以自定义返回类型

resultMap：

column对应数据库中的字段名字，property对应实体类的名字

输入映射parameterType：

可以传入8种基本数据类型，pojo类型，包装pojo类型（pojo类型再次封装），传入map（在映射文件中获取对应的key， #{key}）