Mybatis实现批量插入（存在则更新，不存在则插入数据）有两种情况，一种情况是没有唯一索引，一种是有唯一索引。两种情况的实现方法如下。

没有唯一索引

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<insert id="saveOrUpdate2" >
  <select count(*) as count from user where id = #{id} for update</select>
  <if test="count > 0">
    update user set age = #{age}, name = #{name} where id = #{id}
  </if>
  <if test="count == 0">
    insert into user (age, name) values (#{age}, #{name})
  </if>
</insert>

有唯一索引

唯一索引为name

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<insert id="insertOrUpdateUser" parameterType="User">
  INSERT INTO user (name, age, email)
  VALUES (#{name}, #{age}, #{email})
  ON DUPLICATE KEY UPDATE
  age = VALUES(age),
  email = VALUES(email);
</insert>