error using dbapply

i try this
///
drv<-dbDriver("MySQL")
con<-dbConnect(drv,dbname="prismrsch",user="root",host="localhost",
password="montanha")
query1<-("select account_id, accounttype_cd,account_name from account order
by account_id")
rs <- dbSendQuery(con, query1)

out<- dbApply(rs, INDEX="account_id", FUN =function(x,grp)
quantile(x$account_id,names=FALSE))

//
but i had this message:

Erro em mysqlDBApply(res, ...) : SET_STRING_ELT() can only be applied to a
'character vector', not a 'NULL'

whats is the problem?


-- 
Prof. Aleksandro Montanha
====================

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