sql要怎么调整呢？前端传参user_name输入A没问题，输入‘其他’有这个报错，应该是有数据的

需求：传参为A时展示所有dept；传参‘其他’，展示对应dept。

select distinct dept from T  
where 1=1 
${if(or(len(user_name) == 0,user_name = “A”),””,”and COALESCE((select distinct research from m where login = '" + user_name + "'),'not exists') = dept")} and dept<>''

双引号字符问题, 修改如下:

select distinct dept from T  
where 1=1 
${if(or(len(user_name) == 0,user_name = "A"),"","and COALESCE((select distinct research from m where login = '" + user_name + "'),'not exists') = dept")} and dept<>''