if isnull(@storagecode,'')='1<>1'            
begin            
            
return            
end            
      

if isnull(@storagecode,'')='1<>1'            
begin            
            
return            
end

相当于

select @a1 = '1<>1'
select @a2 = isnull(@storagecode,'')
if @a2 = @a1
begin            
            
return            
end

然后呢
isnull(@storagecode,'')
就是，如果@storagecode 是NULL，也就是没传参数，那么 @a2 ='',否则 @a2 = @storagecode