Mybatis的collection和association

collection：一对多（表关系）

表关系: 库存表 1==>n 货品表,
需求: 查询库存时候,联查出来货品

//库存 实体类【部分属性】
public class Question {@Data
public class StockGoods  extends BaseEntity{private List<GoodsEntity> goodsEntity;/*** 商品编号*/private String goodsId;/*** 商品批号*/private String batchNumber;}

//货品 实体类【部分实体类；采用了JPA注解，若你使用的是mybatis不要写这些注解】
@Entity
@Table(name = "oms_goods")
@IdClass(MasterDataEntityPK.class)
public class GoodsEntity extends BaseEntity implements Serializable {private static final long serialVersionUID = 1L;/*** ERP编号*/@Id@Column(name = "md_number")private String mdNumber;/*** 主数据编码*/@Column(name = "md_code")private String mdCode;

方式一:

代码复用性高, 主表分页查询正确

omsStock.xml

<?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">
<mapper namespace="com.cqp.eop.basic.stock.mapper.OmsStockGoodsMapper"><resultMap id="StockAndGoods" type="com.cqp.eop.basic.stock.entity.StockGoods"><id column="GOODS_ID" jdbcType="VARCHAR" property="goodsId" /><id column="BATCH_NUMBER" jdbcType="VARCHAR" property="batchNumber" /><id column="stockSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="STOCK_NUM" jdbcType="VARCHAR" property="stockNum" /><result column="APP_ID" jdbcType="VARCHAR" property="appId" /><result column="AUTH_CODE" jdbcType="VARCHAR" property="authCode" /><result column="PRODUCTION_DATE" jdbcType="VARCHAR" property="productionDate" /><result column="EXPIRY_DATE" jdbcType="VARCHAR" property="expiryDate" /><result column="SALE_PRICE" jdbcType="VARCHAR" property="salePrice" /><result column="stockCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="stockDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="stockState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="stockOmsBizId" jdbcType="VARCHAR" property="omsBizId" /><result column="ROW_NUM" jdbcType="INTEGER" property="rowNum" /><result column="stockCode" jdbcType="VARCHAR" property="orgCode" /><collection property="goodsEntity" javaType="java.util.ArrayList" ofType="com.cqp.oms.common.upstream.entity.GoodsEntity"><id column="MD_NUMBER" jdbcType="VARCHAR" property="mdNumber" /><id column="goodsSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="MD_CODE" jdbcType="VARCHAR" property="mdCode" /><result column="goodsCode" jdbcType="VARCHAR" property="orgCode" /><result column="GOODS_NAME" jdbcType="VARCHAR" property="goodsName" /><result column="GENERAL_NAME" jdbcType="VARCHAR" property="generalName" /><result column="SPECIFICATION" jdbcType="VARCHAR" property="specification" /><result column="UNIT" jdbcType="VARCHAR" property="unit" /><result column="ALLOW_NO" jdbcType="VARCHAR" property="allowNo" /><result column="PRODUCT_NAME" jdbcType="VARCHAR" property="productName" /><result column="IS_CHINESE_DRUG" jdbcType="VARCHAR" property="isChineseDrug" /><result column="VALIDITY" jdbcType="VARCHAR" property="validity" /><result column="RECOMMENDED_PRICE" jdbcType="VARCHAR" property="recommendedPrice" /><result column="TAX_RATE" jdbcType="VARCHAR" property="taxRate" /><result column="PROVIDER_NAME" jdbcType="VARCHAR" property="providerName" /><result column="PRODUCT_ADDRESS" jdbcType="VARCHAR" property="productAddress" /><result column="DOSAGE_FORM" jdbcType="VARCHAR" property="dosageForm" /><result column="DRUG_TYPE" jdbcType="VARCHAR" property="drugType" /><result column="NATIONAL_PRICE" jdbcType="VARCHAR" property="nationalPrice" /><result column="VENDOR_CODE" jdbcType="VARCHAR" property="vendorCode" /><result column="IS_DELETE" jdbcType="VARCHAR" property="isDelete" /><result column="goodsCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="goodsDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="goodsState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="goodsOmsBizId" jdbcType="VARCHAR" property="omsBizId" /></collection></resultMap>

若表与表之间的字段重名且值不同，要使用别名，至于怎么映射，请看上一篇文章

查询结果：根据 stock.库存数量>=1000000

即：一个库存对用多个商品

{"omsBizId": "INCAPF_1_jl_00000000000000861139","omsCreateDate": "2021-07-20T18:38:22.087+0000","omsDate": "2021-07-22T06:42:05.331+0000","omsStatus": 1,"omsTransError": null,"goodsEntity": [{"omsBizId": "SPZSJ1627529504356","omsCreateDate": "2021-07-29T08:18:20.873+0000","omsDate": "2021-09-07T06:31:41.286+0000","omsStatus": 1,"omsTransError": null,"mdNumber": "1000175454PA","mdCode": "1000175454","orgCode": "PA","goodsName": "泮托拉唑钠肠溶片(vv)","generalName": "泮托拉唑钠肠溶片","specification": "40mg*7`s","unit": "盒","allowNo": null,"productName": "山东罗欣药业集团股份有限公司","isChineseDrug": "0","validity": null,"taxRate": "13% 税","recommendedPrice": null,"providerName": "重庆尚通医药有限公司","productAddress": null,"dosageForm": "肠溶片","drugType": "化学药制剂","nationalPrice": null,"vendorCode": null,"isDelete": "FALSE","systemCode": "10080"},{"omsBizId": "SPZSJ1630313832764","omsCreateDate": "2021-08-30T08:57:14.193+0000","omsDate": "2021-09-07T06:31:41.334+0000","omsStatus": 1,"omsTransError": null,"mdNumber": "1000175454PD","mdCode": "1000175454","orgCode": "PD","goodsName": "泮托拉唑钠肠溶片(vv)","generalName": "泮托拉唑钠肠溶片","specification": "40mg*7`s","unit": "盒","allowNo": null,"productName": "山东罗欣药业集团股份有限公司","isChineseDrug": "0","validity": null,"taxRate": "13% 税","recommendedPrice": "","providerName": "重庆尚通医药有限公司","productAddress": "","dosageForm": "肠溶片","drugType": "化学药制剂","nationalPrice": "","vendorCode": null,"isDelete": "FALSE","systemCode": "10077"},{"omsBizId": "SPZSJ1630313832764","omsCreateDate": "2021-08-30T08:57:14.193+0000","omsDate": "2021-09-07T06:31:41.344+0000","omsStatus": 1,"omsTransError": null,"mdNumber": "1000175454PD","mdCode": "1000175454","orgCode": "PD","goodsName": "泮托拉唑钠肠溶片(vv)","generalName": "泮托拉唑钠肠溶片","specification": "40mg*7`s","unit": "盒","allowNo": null,"productName": "山东罗欣药业集团股份有限公司","isChineseDrug": "0","validity": null,"taxRate": "13% 税","recommendedPrice": "","providerName": "重庆尚通医药有限公司","productAddress": "","dosageForm": "肠溶片","drugType": "化学药制剂","nationalPrice": "","vendorCode": null,"isDelete": "FALSE","systemCode": "10078"},{"omsBizId": "SPZSJ1630313832764","omsCreateDate": "2021-08-30T08:57:14.193+0000","omsDate": "2021-09-07T06:31:41.367+0000","omsStatus": 1,"omsTransError": null,"mdNumber": "1000175454PD","mdCode": "1000175454","orgCode": "PD","goodsName": "泮托拉唑钠肠溶片(vv)","generalName": "泮托拉唑钠肠溶片","specification": "40mg*7`s","unit": "盒","allowNo": null,"productName": "山东罗欣药业集团股份有限公司","isChineseDrug": "0","validity": null,"taxRate": "13% 税","recommendedPrice": "","providerName": "重庆尚通医药有限公司","productAddress": "","dosageForm": "肠溶片","drugType": "化学药制剂","nationalPrice": "","vendorCode": null,"isDelete": "FALSE","systemCode": "10079"}],"goodsId": "1000175454","batchNumber": "1117-02","systemCode": "10079","rowNum": 52,"stockNum": "184","appId": null,"authCode": null,"productionDate": "2020-11-01 00:00:00","expiryDate": "2022-01-01 00:00:00","salePrice": null,"orgCode": null

association：一对一的关系

//库存 实体类【部分属性】
public class Question {@Data
public class StockGoods  extends BaseEntity{private GoodsEntity goodsEntity;/*** 商品编号*/private String goodsId;/*** 商品批号*/private String batchNumber;}

<?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">
<mapper namespace="com.cqp.eop.basic.stock.mapper.OmsStockGoodsMapper"><resultMap id="StockAndGoods" type="com.cqp.eop.basic.stock.entity.StockGoods"><id column="GOODS_ID" jdbcType="VARCHAR" property="goodsId" /><id column="BATCH_NUMBER" jdbcType="VARCHAR" property="batchNumber" /><id column="stockSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="STOCK_NUM" jdbcType="VARCHAR" property="stockNum" /><result column="APP_ID" jdbcType="VARCHAR" property="appId" /><result column="AUTH_CODE" jdbcType="VARCHAR" property="authCode" /><result column="PRODUCTION_DATE" jdbcType="VARCHAR" property="productionDate" /><result column="EXPIRY_DATE" jdbcType="VARCHAR" property="expiryDate" /><result column="SALE_PRICE" jdbcType="VARCHAR" property="salePrice" /><result column="stockCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="stockDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="stockState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="stockOmsBizId" jdbcType="VARCHAR" property="omsBizId" /><result column="ROW_NUM" jdbcType="INTEGER" property="rowNum" /><result column="stockCode" jdbcType="VARCHAR" property="orgCode" /><association property="goodsEntity"javaType="com.cqp.oms.common.upstream.entity.GoodsEntity"><id column="MD_NUMBER" jdbcType="VARCHAR" property="mdNumber" /><id column="goodsSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="MD_CODE" jdbcType="VARCHAR" property="mdCode" /><result column="goodsCode" jdbcType="VARCHAR" property="orgCode" /><result column="GOODS_NAME" jdbcType="VARCHAR" property="goodsName" /><result column="GENERAL_NAME" jdbcType="VARCHAR" property="generalName" /><result column="SPECIFICATION" jdbcType="VARCHAR" property="specification" /><result column="UNIT" jdbcType="VARCHAR" property="unit" /><result column="ALLOW_NO" jdbcType="VARCHAR" property="allowNo" /><result column="PRODUCT_NAME" jdbcType="VARCHAR" property="productName" /><result column="IS_CHINESE_DRUG" jdbcType="VARCHAR" property="isChineseDrug" /><result column="VALIDITY" jdbcType="VARCHAR" property="validity" /><result column="RECOMMENDED_PRICE" jdbcType="VARCHAR" property="recommendedPrice" /><result column="TAX_RATE" jdbcType="VARCHAR" property="taxRate" /><result column="PROVIDER_NAME" jdbcType="VARCHAR" property="providerName" /><result column="PRODUCT_ADDRESS" jdbcType="VARCHAR" property="productAddress" /><result column="DOSAGE_FORM" jdbcType="VARCHAR" property="dosageForm" /><result column="DRUG_TYPE" jdbcType="VARCHAR" property="drugType" /><result column="NATIONAL_PRICE" jdbcType="VARCHAR" property="nationalPrice" /><result column="VENDOR_CODE" jdbcType="VARCHAR" property="vendorCode" /><result column="IS_DELETE" jdbcType="VARCHAR" property="isDelete" /><result column="goodsCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="goodsDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="goodsState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="goodsOmsBizId" jdbcType="VARCHAR" property="omsBizId" /></association ></resultMap>

查询结果：根据 stock.库存数量>=1000000

即：一个库存值对应一个商品

{"omsBizId": "INCAPF_1_jl_00000000000000861139","omsCreateDate": "2021-07-20T18:38:22.087+0000","omsDate": "2021-07-22T06:42:05.331+0000","omsStatus": 1,"omsTransError": null,"goodsEntity": [{"omsBizId": "SPZSJ1627529504356","omsCreateDate": "2021-07-29T08:18:20.873+0000","omsDate": "2021-09-07T06:31:41.286+0000","omsStatus": 1,"omsTransError": null,"mdNumber": "1000175454PA","mdCode": "1000175454","orgCode": "PA","goodsName": "泮托拉唑钠肠溶片(vv)","generalName": "泮托拉唑钠肠溶片","specification": "40mg*7`s","unit": "盒","allowNo": null,"productName": "山东罗欣药业集团股份有限公司","isChineseDrug": "0","validity": null,"taxRate": "13% 税","recommendedPrice": null,"providerName": "重庆尚通医药有限公司","productAddress": null,"dosageForm": "肠溶片","drugType": "化学药制剂","nationalPrice": null,"vendorCode": null,"isDelete": "FALSE","systemCode": "10080"}
}

查询的数据条数变少，只有一条数据

【所以当idea控制台与Navicat所查询的数据条数一样，且postman和浏览器查询的数据行条数与idea、navicat查询的条数对不上，那么就可能是mapper.xml文件的对应关系不正确】

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若想association和collection有相同的效果时association查询出来的数据不被覆盖，那么就在实体类中添加一个能够唯一识别的id，其余不变，因为表中的id不能够唯一识别，所以查询出来的数据行会被覆盖，所以postman的条数和idea的条数不一致

resultMap中只有一个<id>标签，而且只有StockGoods才有<id>标签，<association>标签下没有<id>标签

//库存 实体类【部分属性】
public class Question {@Data
public class StockGoods  extends BaseEntity{private GoodsEntity goodsEntity;private Integer id;//不需要赋值，因为此数据表中也没有此数据，查询出来，都为null/*** 商品编号*/private String goodsId;/*** 商品批号*/private String batchNumber;}

<resultMap id="StockAndGoods" type="com.cqp.eop.basic.stock.entity.StockGoods"><id column="id" property="id"/><result column="GOODS_ID" jdbcType="VARCHAR" property="goodsId" /><result column="BATCH_NUMBER" jdbcType="VARCHAR" property="batchNumber" /><result column="stockSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="STOCK_NUM" jdbcType="VARCHAR" property="stockNum" /><result column="APP_ID" jdbcType="VARCHAR" property="appId" /><result column="AUTH_CODE" jdbcType="VARCHAR" property="authCode" /><result column="PRODUCTION_DATE" jdbcType="VARCHAR" property="productionDate" /><result column="EXPIRY_DATE" jdbcType="VARCHAR" property="expiryDate" /><result column="SALE_PRICE" jdbcType="VARCHAR" property="salePrice" /><result column="stockCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="stockDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="stockState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="stockOmsBizId" jdbcType="VARCHAR" property="omsBizId" /><result column="ROW_NUM" jdbcType="INTEGER" property="rowNum" /><result column="stockCode" jdbcType="VARCHAR" property="orgCode" /><association property="goodsEntity" javaType="com.cqp.eop.basic.goods.entity.GoodsEntity"><result column="MD_NUMBER" jdbcType="VARCHAR" property="mdNumber" /><result column="goodsSysCode" jdbcType="VARCHAR" property="systemCode" /><result column="MD_CODE" jdbcType="VARCHAR" property="mdCode" /><result column="goodsCode" jdbcType="VARCHAR" property="orgCode" /><result column="GOODS_NAME" jdbcType="VARCHAR" property="goodsName" /><result column="GENERAL_NAME" jdbcType="VARCHAR" property="generalName" /><result column="SPECIFICATION" jdbcType="VARCHAR" property="specification" /><result column="UNIT" jdbcType="VARCHAR" property="unit" /><result column="ALLOW_NO" jdbcType="VARCHAR" property="allowNo" /><result column="PRODUCT_NAME" jdbcType="VARCHAR" property="productName" /><result column="IS_CHINESE_DRUG" jdbcType="VARCHAR" property="isChineseDrug" /><result column="VALIDITY" jdbcType="VARCHAR" property="validity" /><result column="RECOMMENDED_PRICE" jdbcType="VARCHAR" property="recommendedPrice" /><result column="TAX_RATE" jdbcType="VARCHAR" property="taxRate" /><result column="PROVIDER_NAME" jdbcType="VARCHAR" property="providerName" /><result column="PRODUCT_ADDRESS" jdbcType="VARCHAR" property="productAddress" /><result column="DOSAGE_FORM" jdbcType="VARCHAR" property="dosageForm" /><result column="DRUG_TYPE" jdbcType="VARCHAR" property="drugType" /><result column="NATIONAL_PRICE" jdbcType="VARCHAR" property="nationalPrice" /><result column="VENDOR_CODE" jdbcType="VARCHAR" property="vendorCode" /><result column="IS_DELETE" jdbcType="VARCHAR" property="isDelete" /><result column="goodsCreateDate" jdbcType="TIMESTAMP" property="omsCreateDate" /><result column="goodsDate" jdbcType="TIMESTAMP" property="omsDate" /><result column="goodsState" jdbcType="INTEGER" property="omsStatus" /><result column="OMS_TRANS_ERROR" jdbcType="VARCHAR" property="omsTransError" /><result column="goodsOmsBizId" jdbcType="VARCHAR" property="omsBizId" /></association>
</resultMap>