MyBatis关联查询（对象嵌套对象）

    Mybatis 查询对象中嵌套其他对象的解决方法有两种，一种是用关联另一个resultMap的形式，如

     

    
   
    	
    	
    	
    
    
    
		
		
		
		
		
		
		
		
		
			
		
		
			
		
	
	
    
    	a.id,
    	a.office_id AS "office.id",
    	a.name,
    	a.enname,
    	a.role_type AS roleType,
	a.data_scope AS dataScope,
	a.remarks,
	a.create_by AS "createBy.id",
	a.create_date,
	a.update_by AS "updateBy.id",
	a.update_date,
	a.del_flag,
    	o.name AS "office.name",
    	o.code AS "office.code",
    	a.useable AS useable,
    	a.is_sys AS sysData
    
    

	SELECT
	
	rm.menu_id AS "menuList.id",
	ro.office_id AS "officeList.id"
	FROM sys_role a
	JOIN sys_office o ON o.id = a.office_id
	LEFT JOIN sys_role_menu rm ON rm.role_id = a.id
	LEFT JOIN sys_role_office ro ON ro.role_id = a.id
	WHERE a.id = #{id}

    

     另一种联合查询 (一对一)的实现，但是这种方式有“N+1”的问题，不建议使用

 

 

 

 
    
    getOfficeById"  resultType="Office">
        select o.name AS "office.name",o.code AS "office.code" from sys_office o where o.id = #{id}
     

    以上就是两种对象内嵌套对象查询的实现。