mybatis主查询给子查询传递参数

当需要将主查询的参数传递给子查询时可以加虚拟列映射
在sql 里 加上 case when (#{selectTagId} IS NULL) then NULL else #{selectTagId} end as selectTagId

        
        
        
        
    


 SELECT d.*,case when (#{selectTagId} IS NULL) then NULL else #{selectTagId} end as selectTagId 
 from ........