SQL Case when 提示列不存在

看网上的案例写法是这样的：

select Behaviortype,count(*)   as count,concat(round(count(*)/3693030*100,2),'%') 比例,
   case  when Behaviortype= 'pv' then 1
         When Behaviortype= ‘cart’ then concat(round((select count from behaviorcount where Behaviortype=‘cart’)/(select count from  behaviorcount where Behaviortype='pv')*100,2),'%')
         when Behaviortype='fav' then concat(round((select count from behaviorcount where Behaviortype='fav')/(select count from behaviorcount where Behaviortype=‘cart’)*100,2),’%’)
         when  Behaviortype='buy'  then concat(round((select count from behaviorcount where Behaviortype=‘buy’)/(select count from behaviorcount where Behaviortype='fav')*100,2),'%')
         end  as 上一阶段比例
         from userbehavior1
         group by Behaviortype
         order by count desc;

但是一直报错提示：
ERROR 1054 (42S22): Unknown column '‘cart’' in 'field list'
但这个字段是有这个取值的
而且我觉得他behaviorcount是一个视图，userbehavior1是原表，也没用任何连接语句，百度了好多没找到解决办法，尝试修改代码如下，还是报同样的错误：

Select *
from(select Behaviortype,count,concat(round(count/3693030*100,2),'%') 比例,
(
case  when Behaviortype= 'pv' then 1
           When Behaviortype= ‘cart’  then concat(round((select count from behaviorcount where Behaviortype=‘cart’)/(select count from  behaviorcount where Behaviortype='pv')*100,2),'%')
           When Behaviortype= ‘fav’  then concat(round((select count from behaviorcount  where Behaviortype=‘fav’)/(select count from  behaviorcount where Behaviortype=‘cart’)*100,2),'%')
           When Behaviortype= ‘buy’  then concat(round((select count from behaviorcount  where Behaviortype=‘buy’)/(select count from  behaviorcount where Behaviortype=‘fav’)*100,2),'%')
End ) 上一阶段占比
from
behaviorcount
group by Behaviortype
order by count desc) a;
ERROR 1054 (42S22): Unknown column '‘cart’' in 'field list'

英文单引号，不是中文单引号

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