关联查询一对多，可以一个实体有多个对多的属性，sql记录会随着关联增多，但是用了mybatis集合会自动合并

迈不过友情╰ 2022-11-24 11:27 36阅读 0赞

left join是线性扩张还是星型扩张看，表之间的join关系，上述一个实体包含多个对多的属性实体，需用星型关连（后续关联项是一对一即可线性） ---sql语句需要有id字段，否则实体自动合并不了

@Data
    @ApiModel(description = "菜单信息根据类别")
    @Accessors(chain = true)
    public class MenuForNewVO {
    
        @ApiModelProperty(value = "商品id", required = true, example = "", position = 0)
        private Long id;
        @ApiModelProperty(value = "商品编码", required = true, example = "", position = 0)
        private String productCode;

<select id="getTemplateCategoryProductListForNew" parameterType="com.mcd.cn.rdc.pcm.product.business.vo.template.TemplateParam"  
          resultMap="templateCategoryProductVOResult">  
    SELECT  
    p.\*, mst.code tab\_code,mst.name tab\_name,mst.image tab\_image,tsp.start\_date,tsp.end\_date  
    FROM  
    t\_template\_category\_product tcp  
    LEFT JOIN t\_product p ON tcp.data\_version = p.data\_version  
    AND tcp.product\_code = p. CODE  
    LEFT JOIN t\_template\_product\_tag tpt ON tcp.data\_version = tpt.data\_version  
    AND tcp.template\_id = tpt.template\_id  
    AND tcp.dimension\_id = tpt.dimension\_id  
    AND tcp.category\_id = tpt.category\_id  
    AND tcp.product\_code = tpt.product\_code  
    LEFT JOIN t\_master\_sales\_tag mst ON tpt.sales\_tag\_code = mst.code  
    and mst.type = 2  
        LEFT JOIN t\_product\_sales\_period tsp ON  p. CODE=tsp.product\_code AND  p.data\_version=tsp.data\_version  
    WHERE  
    tcp.data\_version = \#\{dataVersion\}  
    AND tcp.template\_id = \#\{templateId\}  
    AND tcp.dimension\_id = \#\{dimensionId\}  
    AND tcp.category\_id = \#\{categoryId\}  
    ORDER BY  
    tcp.sort,  
    mst.sort  
  </select>

@Data  
@ApiModel(description = "菜单信息根据类别")  
@Accessors(chain = true)  
public class MenuForNewVO \{

@ApiModelProperty(value = "商品id", required = true, example = "", position = 0)  
    private Long id;

@ApiModelProperty(value = "商品编码", required = true, example = "", position = 0)  
    private String productCode;  
    @ApiModelProperty(value = "菜单商品显示名称中文", required = true, notes = "如：麦麦脆汁鸡2块", position = 1)  
    private String productNameCn;  
    @ApiModelProperty(value = "菜单商品显示名称英文", notes = "如：McCrispy Chicken-2pcs", position = 2)  
    private String productNameEn;  
    @ApiModelProperty(value = "价格组redis存储key", required = true, notes = "redis存储key", example = "", position = 3)  
    private String priceGroupInfo;

@ApiModelProperty(value = "商品图片相对路径redis存储key", required = true, notes = "只有图片名称，图片路径需要前台配置redis存储key", example = "", position = 4)  
    private String productImage;

@ApiModelProperty(value = "菜品类别", required = true, notes = "1：单品 2：套餐 3：产品组", position = 11,allowableValues = "1,2,3")  
    private String productType;  
    @ApiModelProperty(value = "售卖标识", required = true, notes = "1:可卖,0:不可买,2:隐藏", position = 12,allowableValues = "0,1,2")  
    private String saleFlag;  
    @ApiModelProperty(value = "商品组的前端交互方式", required = true, notes = "1：单品到详情页；2：产品组到详情页", position = 13,allowableValues = "1,2")  
    private String  uiType;  
    @ApiModelProperty(value = "商品组对象", required = true, notes = "如果单品中存在特制属性，也需要在产品组对象中有值", example = "", position = 14)  
    private List<ProductGroupVO> productGroupList;  
    private List<TagVO> productTagList;

private List<ProductSalesPeriodVO> productPeriodList;

@JsonIgnore  
    private String daypart;  
    @JsonIgnore  
    private String salesPeriod;  
    @JsonIgnore  
    private String salesTime;  
\}

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参考：

https://blog.csdn.net/qq87034246/article/details/79878850

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