mybatis条件查询语句

经常见到前端页面上有列表展示数据的形式。有的列表每一个字段列可能都会配有一个上三角下三角按钮，提示该列数据正序或者倒叙排列，对应的sql的关键字就是asc，desc。以下给出一个模板。

<?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">
<!--这里命名空间对应你dao接口的路径-->
<mapper namespace="com.xxx.xxx.xx.xxx.dao.xxxDao">
    <resultMap id ="aaaaMap" type="com.xxx.xxx.xx.xxx.dao.vo.xxxVo">
        <!--一下字段为列举字段，property对应Vo字段，column对应表字段-->
        <id property="userId" column="user_id">
        <result property="userName" column="user_name">
        <result property="userAge" column="user_age">
    </resultMap>
    <select id="getVoInfo" parameterType="",resultMap="aaaaMap">
        select 
        user_id,
        user_name,
        user_age
        from user
        <if test="orderByColumn != null and orderByColumn != ''">
            order by 
            <choose>
                <when test="orderByColumn == 'userId'">
                    user_id
                </when>
                <when test="orderByColumn == 'userName'">
                    user_Name
                </when>
                <when test="orderByColumn == 'userAge'">
                    user_Age
                </when>
                <otherwise>
                    user_id
                </otherwise>
            </choose>
            <if test="orderByDirection != null and orderByDirection != ''">
                <choose>
                    <when test="orderByDirection == desc">
                        desc
                    <wehen>
                    <otherwise>
                        asc
                    </otherwise>
                </choose>
            </if>
        </if>
    </select>

那么前端传给你的参数有这两个字段了。举例：{”orderByColumn“:"userId","orderByDirection="desc""}。