经过前面两个章节讲解，对mybatis应该有了大概了解，今天讲解下mapper文件的使用：
主要是select查询语句where条件的判断：
bigint类型的判空：

<if test="pkId != null">
  and PK_ID = #{pkId}
 </if>

varchar类型的判空：

<if test="listRemark != null and listRemark != ''">
 and LIST_REMARK = #{listRemark}
</if>

datetime类型的判空：

<if test="createOper != null and createOper != ''">
    and CREATE_OPER = #{createOper}
</if>

in语句的使用：

<if test="payWay != null and payWay != ''">
    and PAY_WAY in ${payWay}
</if>

like语句的使用：

<if test="fromTradeName != null and fromTradeName != ''">
    and FROM_TRADE_NAME like CONCAT('%', #{fromTradeName},'%')
</if>

CREATE_DATE时间间隔查询：

<if test="createDate != null">
    <![CDATA[ and #{createDate} <= CREATE_DATE]]>
</if>
<if test="modifyDate != null">
    <![CDATA[ and CREATE_DATE <=  #{modifyDate}]]>
</if>

或者：

<if test="beginTime != null and beginTime != ''"><!-- 开始时间检索 -->
  AND date_format(u.create_time,'%y%m%d') >= date_format(#{beginTime},'%y%m%d')
</if>
<if test="endTime != null and endTime != ''"><!-- 结束时间检索 -->
  AND date_format(u.create_time,'%y%m%d') <= date_format(#{endTime},'%y%m%d')
</if>

批量删除：

<delete id="deleteUserByIds" parameterType="Long">
  update sys_user set del_flag = '2' where user_id in
  <foreach collection="array" item="userId" open="(" separator="," close=")">
    #{userId}
      </foreach> 
</delete>

对应接口：

public int deleteUserByIds(Long[] userIds);