result_create（conn @ ptr，statement）中的错误：“ as”附近：语法错误

Question

我运行了以下查询，但无法理解该错误。

data <- 
sqldf('SELECT Contract_Code,
sum(case when format(as.Date(status_dt)),"%Y-%m")= format(as.Date(AddMonths(Start_date,0))), "%Y-%m") 
then Late_days else NULL end) as F01
from df11 
group by Contract_Code')

Error in result_create(conn@ptr, statement) : near "as": syntax error