SQL —— java寫出結果集爲一對多關係的sql

一、結果集展示—摸清需求，搞清楚最終結果

很明顯，我們要的結果是一對多的結果，如何使用一條sql查出來呢
controller返回json 本文最後寫

二、設計實體類—用於封裝sql返回結果

三、書寫SQL

圖片展示說明

具體sql代碼分析

此處不採取常規的sql查詢方式，而是將返回結果在resultMap中，進行一對多拆分
collection 中用於存放我們想要的“一對多”中的“多”。也就是我們實體類中的List<> result

mapper.xml

<mapper namespace="picc.web.enterpriseinquiries.dao.DwPolicyInfoDao">
    <resultMap id="dw_policy_info" type="picc.web.enterpriseinquiries.entity.DwPolicyInfo2" >
        <result column="uw_end_date" property="uwEndDate" jdbcType="VARCHAR" />
        <result column="total_premium" property="totalPremium" jdbcType="VARCHAR" />
        <result column="rec_premium" property="recPremium" jdbcType="VARCHAR" />
    </resultMap>
    <resultMap id="codeResultMap" type="picc.web.enterpriseinquiries.entity.Code" >
        <result column="organizeCode" property="organizeCode" jdbcType="VARCHAR" />
        <result column="comCode" property="comCode" jdbcType="VARCHAR" />
    </resultMap>
    <!--近5年簽單保費和應收保費分佈情況-->
    <select id="GetTotalRecPremiumCase" resultMap="resultMap" parameterType="picc.web.enterpriseinquiries.entity.Code">
        select DISTINCT (riskcode) as riskcode,organize_code as organizeCode,make_com as comCode,order_no
        from  dw_policy_info
        where  uw_end_date >=  year(current) - 4
        and organize_code =  #{organizeCode}
        <if test="comCode!= null and  comCode!=''" >
            and make_com = #{comCode}
        </if>
        group by uw_end_date,riskcode,organize_code,make_com
    </select>
    <resultMap id="resultMap" type="picc.web.enterpriseinquiries.entity.DwPolicy" extends="codeResultMap">
        <result column="riskCode" property="riskCode" jdbcType="VARCHAR" />
        <result column="organizeCode" property="organizeCode" jdbcType="VARCHAR" />
        <result column="comCode" property="comCode" jdbcType="VARCHAR" />
        <collection property="value" ofType="picc.web.enterpriseinquiries.entity.DwPolicyInfo2" column="{organizeCode=organizeCode,riskCode=riskCode, comCode=comCode}" select="getDwPolicy"></collection>  <!--傳多個參數-->
					
		
		
    </resultMap>
    <select id="getDwPolicy" resultType="picc.web.enterpriseinquiries.entity.DwPolicyInfo2" parameterType="java.util.Map">
        select  uw_end_date as uwEndDate,
        nvl(round(sum(total_premium) *0.0001,2),0)  totalPremium ,
        nvl(round(sum(rec_premium)*0.0001,2),0)   recPremium
                from  dw_policy_info
                where  uw_end_date >=  year(current) - 4
                and organize_code = #{organizeCode}
                and riskcode=#{riskCode}
                <if test="comCode!= null and  comCode!=''" >
                    and make_com = #{comCode}
                </if>
                group by uw_end_date
    </select>
   
</mapper>

四、Controller

返回json類型的結果給頁面，此處用了JSONObject.toJSONString(）
引入jar包

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.47</version>
</dependency>

@RequestMapping("/GetTotalRecPremiumCase")
    @ResponseBody
    public String GetTotalRecPremiumCase(HttpServletRequest request){
        HeadResponse hr = new HeadResponse();
        hr.setMessage("查詢失敗！");
        hr.setStatus("500");
        List<DwPolicyInfo2> list = new ArrayList<>();
        Code code = new Code();
        try {
            code = PassParamtersUtil.GetCode(request,dwPolicyInfoService);
            String organizeCode = code.getOrganizeCode();
            String comCode = code.getComCode();
            Code code2 = new Code();
            code2.setOrganizeCode(organizeCode);
            code2.setComCode(comCode);
            list = dwPolicyInfoService.GetTotalRecPremiumCase(code2);
            hr.setMessage("查詢成功！");
            hr.setStatus("200");
            hr.setResult(list);
            return JSONObject.toJSONString(hr);
        }catch (Exception e){
            System.out.println("e:"+e);
            return JSONObject.toJSONString(hr);
        }
    }

返回結果展示

這裏的 1 2 3 4等數字 對應sql那張圖裏的查詢結果