R sprintf in sqldf's like

问题

I would like to do a looping query in R using sqldf to that select all non-NULL X.1 variable with date "11/12/2015" and at 9AM. Example :

StartDate              X.1
11/12/2015 09:14        A
11/12/2015 09:36        
11/12/2015 09:54        A

The date is in variable that generated from other query

nullob<-0
dayminnull<-as.numeric(sqldf("SELECT substr(Min(StartDate),1,03)as hari     from testes")) # this produce "11/12/2015"
  for (i in 1 : 12){
    dday<-mdy(dayminnull)+days(i) #go to next day
    sqlsql <- sprintf("SELECT count([X.1]) FROM testes where StartDate like '% \%s 09: %'", dday)
    x[i]<-sqldf(sqlsql)
    nullob<-nullob+x[i]
}

And it comes with error : Error in sprintf("SELECT count([X.1]) FROM testes WHERE StartDate like '%%s 09%'", : unrecognised format specification '%' Please hellp. thank you in advance

回答1:

It's not super clear in the documentation, but a % followed by a %, that is %%, is the way to tell sprintf to use a literal %. We can test this fairly easily:

sprintf("%% %s %%", "hi")
[1] "% hi %"

For your query string, this should work:

sprintf("SELECT count([X.1]) FROM testes where StartDate like '%% %s 09: %%'", dday)

From ?sprintf:

The string fmt contains normal characters, which are passed through to the output string, and also conversion specifications which operate on the arguments provided through .... The allowed conversion specifications start with a % and end with one of the letters in the set aAdifeEgGosxX%. These letters denote the following types:

... [Documentation on aAdifeEgGosxX]

%: Literal % (none of the extra formatting characters given below are permitted in this case).

来源：https://stackoverflow.com/questions/36881669/r-sprintf-in-sqldfs-like

标签

printf

sqldf