You're correct. It does work. I was looking at some other result printed. My
bad.
Looks like we can also get the same result using 'SELECT changes()'.
Approach 1:
con <- data.frame(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
sqldf()
suppressWarnings(sqldf(c(" update con set V1 = 0 where V1 > 5 ", "select
changes()")))
sqldf("select * from main.con")
sqldf()
Approach 2:
con <- data.frame(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
sqldf()
suppressWarnings(sqldf(c("pragma count_changes = 1", "update con set V1 = 0
where V1 > 5 ")))
sqldf("select * from main.con")
sqldf()
-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com]
Sent: Thursday, June 11, 2020 10:30 AM
To: Ravi Jeyaraman <rav...@gmail.com>
Cc: r-help@r-project.org
Subject: Re: [R] sqldf and number of records affected
There is no real difference between your example and the example I provided.
Both use a data.frame in R and both work for me under R 3.5 with RSQLite 2.2.0
See log below.
Note that there is a bug in R 4.0 related to tcltk that could possibly affect
sqldf as it uses tcltk. A fix has been announced for R 4.0.2.
> library(sqldf)
Loading required package: gsubfn
Loading required package: proto
Loading required package: RSQLite
> con <- data.frame(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
> sqldf()
<SQLiteConnection>
Path: :memory:
Extensions: TRUE
> sqldf(c("pragma count_changes = 1", "update con set V1 = 0 where V1 >
> 5 "))
rows updated
1 5
Warning message:
In result_fetch(res@ptr, n = n) :
SQL statements must be issued with dbExecute() or dbSendStatement() instead
of dbGetQuery() or dbSendQuery().
> ans <- sqldf("select * from main.con")
> sqldf()
NULL
> ans
V1
1 1
2 2
3 3
4 4
5 5
6 0
7 0
8 0
9 0
10 0
> R.version.string
[1] "R version 3.5.3 (2019-03-11)"
> packageVersion("sqldf")
[1] ‘0.4.11’
> packageVersion("RSQLite")
[1] ‘2.2.0’
> packageVersion("DBI")
[1] ‘1.1.0’
On Thu, Jun 11, 2020 at 10:06 AM Ravi Jeyaraman <rav...@gmail.com> wrote:
>
> Thanks for the response Gabor. Looks like the below example will work when
> using SQLite, but in my case I'm just creating a dataframe in R and trying to
> update it using sqldf as below and it doesn't seem to work ...
>
> con <- data.frame(V1 = c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
> sqldf()
> sqldf(c("pragma count_changes = 1", "update con set V1 = 0 where V1 >
> 5 ")) ans <- sqldf("select * from main.con")
> sqldf()
>
> -----Original Message-----
> From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com]
> Sent: Thursday, June 11, 2020 9:12 AM
> To: Ravi Jeyaraman <rav...@gmail.com>
> Cc: r-help@r-project.org
> Subject: Re: [R] sqldf and number of records affected
>
> Here is an example. Ignore the warning or use the workaround
> discussed here
> https://github.com/ggrothendieck/sqldf/issues/40
> to avoid the warning.
>
> library(sqldf)
> sqldf() # use same connection until next sqldf()
> sqldf(c("pragma count_changes = 1", "update BOD set demand = 99 where Time
> > 4"))
> sqldf("select * from main.BOD")
> sqldf()
>
>
> On Thu, Jun 11, 2020 at 9:01 AM Ravi Jeyaraman <rav...@gmail.com> wrote:
> >
> > Hello all, When I execute a SQL using SQLDF, how do I get the number
> > of records affected? I mean, if I run an UPDATE on a data frame, it
> > doesn't tell me if and how many records got updated. I've read
> > through the documentation and there don't seem to be a way to get
> > this info unless it's done on a database. Any ideas?
> >
> > Thanks
> > Ravi
> >
> >
> > --
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>
>
>
> --
> Statistics & Software Consulting
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--
Statistics & Software Consulting
GKX Group, GKX Associates Inc.
tel: 1-877-GKX-GROUP
email: ggrothendieck at gmail.com
______________________________________________
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