R help - Jul 2012 - Passing Multiple Variable Into SQLDF Statement as parameters of function

Hey guys,

So I'm working with a project where I manage a database within R, and
I'm
developing a script/function that will automatically run my queries in R
depending on the date parameters passed in.

The problem is that when I create variables for the dates, and use those
variables in my sqldf statements, R says that there is no such column in the
dataframe (which is true!). My question is: how can I pass multiple date
variables into my sqldf statements? In particular, the sqldf is supposed to
read the date parameter as a character string (its the only way I could get
it to work). 

This is my code so far:
> StartDate='2010-06-15'
> EndDate='2010-06-22'
> Example=paste("select * from LibDB where Date_Entered
> =",as.character(StartDate))
> sqldf(Example,verbose=TRUE)
This passes the StartDate in correctly, but in a form where my particular
query won't pick up the date in the database. In reality, I want it to act
as the following:
> Example=paste("select * from LibDB where Date_Entered
='2010-06-15'")
Eventually, I need to have statements such as:
> Example=paste("select * from LibDB where Date_Entered  between
> '2010-06-15' and '2010-06-22')
Thanks in advance for any feedback! :)


--
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Sent from the R help mailing list archive at Nabble.com.

On Wed, Jul 11, 2012 at 11:16 AM, scstrein <scstrein at ncsu.edu>
wrote:
> Hey guys,
>
> So I'm working with a project where I manage a database within R, and
I'm
> developing a script/function that will automatically run my queries in R
> depending on the date parameters passed in.
>
> The problem is that when I create variables for the dates, and use those
> variables in my sqldf statements, R says that there is no such column in
the
> dataframe (which is true!). My question is: how can I pass multiple date
> variables into my sqldf statements? In particular, the sqldf is supposed to
> read the date parameter as a character string (its the only way I could get
> it to work).
>
> This is my code so far:
>
>> StartDate='2010-06-15'
>> EndDate='2010-06-22'
>
>> Example=paste("select * from LibDB where Date_Entered
>> =",as.character(StartDate))
>> sqldf(Example,verbose=TRUE)
>
> This passes the StartDate in correctly, but in a form where my particular
> query won't pick up the date in the database. In reality, I want it to
act
> as the following:
>
>> Example=paste("select * from LibDB where Date_Entered
='2010-06-15'")
>
> Eventually, I need to have statements such as:
>
>> Example=paste("select * from LibDB where Date_Entered  between
>> '2010-06-15' and '2010-06-22')
>
See example 5 on the sqldf home page;
http://code.google.com/p/sqldf/#Example_5._Insert_Variables
-- 
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com

You have to explicitly add the quotes:

 Example=paste0("select * from LibDB where Date_Entered
='",as.character(StartDate), "'") # notice the single
quotes within
the double quotes
> sqldf(Example,verbose=TRUE)
On Wed, Jul 11, 2012 at 11:16 AM, scstrein <scstrein at ncsu.edu>
wrote:
> Hey guys,
>
> So I'm working with a project where I manage a database within R, and
I'm
> developing a script/function that will automatically run my queries in R
> depending on the date parameters passed in.
>
> The problem is that when I create variables for the dates, and use those
> variables in my sqldf statements, R says that there is no such column in
the
> dataframe (which is true!). My question is: how can I pass multiple date
> variables into my sqldf statements? In particular, the sqldf is supposed to
> read the date parameter as a character string (its the only way I could get
> it to work).
>
> This is my code so far:
>
>> StartDate='2010-06-15'
>> EndDate='2010-06-22'
>
>> Example=paste("select * from LibDB where Date_Entered
>> =",as.character(StartDate))
>> sqldf(Example,verbose=TRUE)
>
> This passes the StartDate in correctly, but in a form where my particular
> query won't pick up the date in the database. In reality, I want it to
act
> as the following:
>
>> Example=paste("select * from LibDB where Date_Entered
='2010-06-15'")
>
> Eventually, I need to have statements such as:
>
>> Example=paste("select * from LibDB where Date_Entered  between
>> '2010-06-15' and '2010-06-22')
>
> Thanks in advance for any feedback! :)
>
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Passing-Multiple-Variable-Into-SQLDF-Statement-as-parameters-of-function-tp4636147.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.


-- 
Jim Holtman
Data Munger Guru

What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.