mybatis-mapper.xml 增删改查SQL详解

<?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="com.example.mybatisdemo.daomapper.StudentMapper">
  <resultMap id="BaseResultMap" type="com.example.mybatisdemo.entity.Student">
    <result column="id" jdbcType="INTEGER" property="id" />
    <result column="name" jdbcType="VARCHAR" property="name" />
    <result column="age" jdbcType="INTEGER" property="age" />
    <result column="sex" jdbcType="CHAR" property="sex" />
  </resultMap>
//--以上内容是自动生成得

//插入一条新得数据，部分字段更新
//parameterType  入参是对象

<insert id="insertStudent" parameterType="com.example.mybatisdemo.entity.Student">

  insert into mysql_student ( name, age, sex)
  values  (#{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER},
    #{sex,jdbcType=CHAR})
</insert>

//插入一条新得数据，每个字段都更新切判断

//useGeneratedKeys="true"  keyProperty="id":当主键id是自增的情况下，添加一条记录的同时，我们要获取到主键id。
// <trim prefix="(" suffix=")" suffixOverrides=","> ,prefix:在trim标签内sql语句加上前缀"(",suffix:在trim标签内sql语句加上后缀")",suffixOverrides:指定去除多余的后缀内容","

<insert id="insertSelective" parameterType="com.example.mybatisdemo.entity.Student"  useGeneratedKeys="true"
        keyProperty="id">
  insert into mysql_student
  <trim prefix="(" suffix=")" suffixOverrides=",">
    <if test="id != null">
      id,
    </if>
    <if test="name != null">
      name,
    </if>
    <if test="age != null">
      age,
    </if>
    <if test="sex != null">
      sex,
    </if>
  </trim>
  <trim prefix="values (" suffix=")" suffixOverrides=",">
    <if test="id != null">
      #{id,jdbcType=INTEGER},
    </if>
    <if test="name != null">
      #{name,jdbcType=VARCHAR},
    </if>
    <if test="age != null">
      #{age,jdbcType=INTEGER},
    </if>
    <if test="sex != null">
      #{sex,jdbcType=CHAR},
    </if>
  </trim>
</insert>
-------------------------------------------------------------------------

//修改，每个字段判空
<update id="update" parameterType="addressMappingDto">
    update address_base
    <set>
        <trim prefix="" suffix="" suffixOverrides=",">
            <if test="road != null">
                road = #{road,jdbcType=VARCHAR},
            </if>
            <if test="stationId != null">
                station_id = #{stationId,jdbcType=INTEGER},
            </if>
            <if test="stationName != null and stationName !=''">
                station_name = #{stationName,jdbcType=VARCHAR},
            </if>
            update_time = now(),
            update_user = #{updateUser,jdbcType=VARCHAR}
        </trim>
    </set>
    where id = #{id,jdbcType=BIGINT}
    AND is_delete = 0
</update>

//简单得update

<update id="updateUser" parameterType="com.example.mybatisdemo.entity.Student">
  update mysql_student
  set name = #{name,jdbcType=VARCHAR},
  age = #{age,jdbcType=INTEGER},
  sex = #{sex,jdbcType=CHAR}
  where id = #{id,jdbcType=INTEGER}
</update>

-----------------------------------------------------------

<!-- 删除实体 -->
<update id="delete" parameterType="addressMappingDto">
    update address_base
    <set>
        is_delete = 1,
        update_time = now(),
        update_user = #{updateUser,jdbcType=VARCHAR}
    </set>
    where id = #{id,jdbcType=BIGINT}
    AND is_delete = 0
</update>

<delete id="deleteUserById" parameterType="java.lang.Integer">
  delete from mysql_student
  where id = #{id,jdbcType=INTEGER}
</delete>
------------------------------------------------------
//查询根据id

<select id="selectStudentId" parameterType="java.lang.Integer" resultMap="BaseResultMap">
  select  * from mysql_student where  id = #{id,jdbcType=INTEGER}
</select>
//查询多条件
<select id="getUserByCondition" parameterType="java.lang.String" resultMap="BaseResultMap">
  select  * from mysql_student where  name = #{name,jdbcType=VARCHAR} and age=#{age,jdbcType=INTEGER}
</select>

//根据条件查询一个实体
<select id="findOneByCky2AndAddress" resultMap="BaseResultMap"
        parameterType="addressMappingDto">
    select
    id,
    province_id,
    city_id,
    county_id,
    town_id,
    cky2,
    address,
    road,
    station_id,
    station_name
    from address_base
    where cky2 = #{cky2,jdbcType=INTEGER}
    AND address = #{address,jdbcType=VARCHAR}
    AND is_delete = 0
    ORDER BY id DESC LIMIT 1
</select>