业务：通常主表从表 查询，一对多关系，通常是先查主表，然后拿主表的 关联字段与从表关联。在代码中  通常用for  循环等方法给   从表的数据赋值，很麻烦，，，很麻烦。。。。

用mybatis的一对多完全解决上面这个鸡肋操作

1.接口

    /***   TODO 集合测试*/@ApiOperationSupport(order = 100)@ApiOperation(value = "集合测试列表")@GetMapping("/listtest")public TableDataInfo listtest(CmrxRpmProject cmrxRpmProject) {startPage();List<CmrxRpmProject> list = cmrxRpmProjectService.listtest(cmrxRpmProject);return getDataTable(list);}

2.实体类

3.mybatis

3.1 对象关系映射

    <resultMap type="CmrxRpmProject" id="CmrxRpmProjectResult"><id property="id"    column="id"    /><result property="id"    column="id"    /><result property="sbdw"    column="sbdw"    /><result property="xmmc"    column="xmmc"    /><result property="lxr"    column="lxr"    /><!--TODO 集合测试--><collection property="cmrxRpmProjectresultsList" ofType="CmrxRpmProjectresults"><id property="id" column="bid"/><result property="ctCgxsname"    column="ct_cgxsname"    /><result property="cgxs"    column="cgxs"    /></collection></resultMap>

3.2 数据查询

    <select id="listtest"  resultMap="CmrxRpmProjectResult">selecta.id, a.sbdw, a.xmmc, a.lxr, a.lxdh, a.ksn, a.ksy, a.jsn, a.jsy, a.xmry, a.ptjf, a.zdzz, a.zczj, a.ztr, a.xmbj, a.yjnr,a.yjyy, a.jsgj, a.xyjc, a.khzb, a.cxd,a.sblb, a.lxzt, a.yszt, a.yswd, a.lrbm, a.uid, a.lrsj, a.gdzt, a.yssq,b.ct_cgxsname, b.cgmc, b.cgxs,b.id as bidfrom psms.cmrx_rpm_project as a left join psms.cmrx_rpm_projectresults as b on a.id = b.idp</select>

4.数据返回结构