MyBatis多表关联查询

1：最简单粗暴的笨办法就是自定义一个智能的实体类，把多表查询需要的字段列出属性，注意实体类的属性名和数据库字段名保持一致

2：两个表一对多关联

实体类

public class BasicInfo{
    private Integer basicInfoId;
    private Integer projectId;//项目ID
    private String keyNo;//公司内部关联主键
    private String name;//企业名称
    private String no;//注册号
    private String belongOrg;//登记机关
    private String operName;//法定代表人
    private String startDate;//成立日期
    private String endDate;//注销/吊销日期
    private String status;//登记状态（存续、在业、注销、迁入、吊销、迁出、停业、清算）
    private String province;//所在省份缩写
    private String updateDate;//更新日期
    private String creditCode;//统一社会信用代码
    private String registCapi;//注册资本
    private String econKind;//类型
    private String address;//住所
    private String scope;//经营范围
    private String termStart;//营业期限自
    private String teamEnd;//营业期限至
    private String checkDate;//核准日期
    private String sysTime;//
    private List<ChangeRecords> changeRecordsList;  //变更记录 
    .....

public class ChangeRecords {
    private Integer changeRecordsId;
    private Integer basicInfoId;
    private String projectName;
    private String beforeContent;
    private String afterContent;
    private String changeDate;
    public Integer getChangeRecordsId() {
        return changeRecordsId;
    }
    public void setChangeRecordsId(Integer changeRecordsId) {
        this.changeRecordsId = changeRecordsId;
    }
    public String getProjectName() {
        return projectName;
    }
    public void setProjectName(String projectName) {
        this.projectName = projectName;
    }
    public String getBeforeContent() {
        return beforeContent;
    }
    public void setBeforeContent(String beforeContent) {
        this.beforeContent = beforeContent;
    }
    public String getAfterContent() {
        return afterContent;
    }
    public void setAfterContent(String afterContent) {
        this.afterContent = afterContent;
    }
    public String getChangeDate() {
        return changeDate;
    }
    public void setChangeDate(String changeDate) {
        this.changeDate = changeDate;
    }
	public Integer getBasicInfoId() {
		return basicInfoId;
	}
	public void setBasicInfoId(Integer basicInfoId) {
		this.basicInfoId = basicInfoId;
	}
}

xml文件

<resultMap id="BaseResultMap" type="com.cybernaut.core.model.BasicInfo" >
	    <id column="basic_info_id" property="basicInfoId" jdbcType="INTEGER" />
	    <result column="project_id" property="projectId" jdbcType="INTEGER" />
	    <result column="key_no" property="keyNo" jdbcType="VARCHAR" />
	    <result column="name" property="name" jdbcType="VARCHAR" />
	    <result column="no" property="no" jdbcType="VARCHAR" />
	    <result column="belong_org" property="belongOrg" jdbcType="VARCHAR" />
	    <result column="oper_name" property="operName" jdbcType="VARCHAR" />
	    <result column="start_date" property="startDate" jdbcType="VARCHAR" />
	    <result column="end_date" property="endDate" jdbcType="VARCHAR" />
	    <result column="status" property="status" jdbcType="VARCHAR" />
	    <result column="province" property="province" jdbcType="VARCHAR" />
	    <result column="update_date" property="updateDate" jdbcType="VARCHAR" />
	    <result column="credit_code" property="creditCode" jdbcType="VARCHAR" />
	    <result column="regist_capi" property="registCapi" jdbcType="VARCHAR" />
	    <result column="econ_kind" property="econKind" jdbcType="VARCHAR" />
	    <result column="address" property="address" jdbcType="VARCHAR" />
	    <result column="scope" property="scope" jdbcType="VARCHAR" />
	    <result column="term_start" property="termStart" jdbcType="VARCHAR" />
    	<result column="team_end" property="teamEnd" jdbcType="VARCHAR" />
    	<result column="check_date" property="checkDate" jdbcType="VARCHAR" />
    	<result column="sys_time" property="sysTime" jdbcType="VARCHAR" />
    	<!-- 变更记录 -->
    	<collection property="changeRecordsList" ofType="com.cybernaut.core.model.ChangeRecords" column="basic_info_id" 
          select="change_records.selectByChangeRecordsId"></collection>	
	</resultMap>
	<sql id="Base_Column_List" >
	    basic_info_id, project_id, key_no, name, no, belong_org, oper_name, start_date, end_date, 
	    status, province, update_date, credit_code, regist_capi, econ_kind, address, scope, 
	    term_start, team_end, check_date, sys_time
	</sql>

3：一对一

basic实体类里面的list改成单个对象

xml文件里<collection...>改成

<association property="对象名称" javaType="
com.cybernaut.core.model.ChangeRecords
" column="basic_info_id" select="change_records.selectSupervisor"/>



另外一种方式

<association property="对象名称" javaType="
com.cybernaut.core.model.ChangeRecords"
resultMap="changeRecordsResultMap"/></resultMap><!--教师实体映射--><resultMap id="changeRecordsResultMap" type="com.cybernaut.core.model.ChangeRecords"><id property="id" column="t_id"/><result property="name" column="t_name"/><result property="gender"
 column="t_gender"/><result property="researchArea" column="t_research_area"/><result property="title" column="t_title"/></resultMap>