Mybatis实现多表关联多条件查询

1.在实体类中添加需要展示的但在数据库表结构中字段

2.在mapper.xml的

定义需要展示的列

3.在SQL中关联查询即可

SELECT m.id,m.title,c.company,c.hierarchy,m.score,l.file_path,t.project_name,t.contents,m.file_id FROM material_info mLEFT JOIN company c ON m.company_id=c.id AND c.data_state='Normal'LEFT JOIN t_system t ON m.evaluation_id=t.id AND m.data_state='Normal'LEFT JOIN file_message l ON l.id=m.file_id AND l.data_state='Normal'm.data_state='Normal'AND t.nd=#{nd}AND t.project_name=#{projectName}

4.在mapper.java 中编写代码:

List selectByMap(String nd,String projectName);

不需要在实体类添加属性，也不需要在定义列

1.在SQL中关联查询

SELECT s.companyid,s.yz_code,c.company,s.survey_name,s.start_time,s.end_time,s.qr_code FROM survey_info s JOIN company c ON s.companyid=c.idWHERE 1 = 1 AND s.data_state = 'Normal'AND c.company LIKE CONCAT('%',#{param1},'%')AND s.companyid=#{param2} 
2.在mapper.java 中编写代码:
 
 
 
List> getSurveyInfoList(String dwmc, Long id);