mybatis循环遍历集合以及使用多个参数对象的sql配置
1、mybatis循环删除数据的sql循环删除时,要求相应的Mapper方法传递的参数是一个集合(如List),在<delete>标签的参数中设置parameterType="java.util.List",书写sql语句时,使用<foreach>标签循环,其中collection表示Mapper中传递的参数名,item便是循环时压入栈顶的元素,open表示第一次加入的sql前缀,separator表示集合中每个元素之间的分隔符,colse表示循环结束时为sql语句添加的后缀。具体配置如下:
<delete id="deleteList" parameterType="java.util.List">
DELETE FROM CITY WHERE 1 = 1
<foreach collection="list" item="item" open="AND CITY_NO IN(" separator="," close=")">
#{item.cityNo}
</foreach>
</delete>
2、mybatis中Mapper方法传递多个参数对象
如果在Mapper中的方法中传递了多个参数对象,可以在service层进行封装(系统的流程为controller->service->mapper),将多个参数封装到map中,用key值进行区别,然后在mapper.xml中的配置如下:
<select id="findByPage" resultMap="listCityMap" parameterType="java.util.Map">
SELECT CITY_NO, CITY_NAME, PROVINCE_NO FROM CITY WHERE 1 = 1
<if test="city.cityNo != null and city.cityNo != '' ">
AND CITY_NO = #{city.cityNo}
</if>
<if test="city.cityName != null and city.cityName != ''">
AND CITY_NAME = #{city.cityName}
</if>
<if test="city.provinceNo != null and city.provinceNo != ''">
AND PROVINCE_NO = #{city.provinceNo}
</if>
LIMIT #{page.startRowNum}, #{page.pageSize}
</select>
其中在Mapper.xml的<select>标签的参数中设置parameterType="java.util.Map",在service方法中,有page和city2个形参,故在service的方法中进行如下处理:
public List<City> findByPage(SimplePage page, City city) {
Map<String, Object> paramMap = new HashMap<String, Object>();
paramMap.put("page", page);
paramMap.put("city", city);
return cityMapper.findByPage(paramMap);
}
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