Re: [R] sqlSave() and rownames=TRUE makes my Rgui crash

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Fri 09 Jun 2006 - 23:53:49 EST

On 6/9/2006 9:42 AM, Lapointe, Pierre wrote:

> On 6/9/2006 8:51 AM, Lapointe, Pierre wrote:

>> Hello,
>>
>> I created a table in MySQL with this command
>>
>> CREATE TABLE example (pk INT NOT NULL AUTO_INCREMENT,PRIMARY KEY(pk),
>> id VARCHAR(30),col1 VARCHAR(30),col2 VARCHAR(30))
>>
>> ### In R, I can connect to this table:
>>
>> library(DBI)
>> library(RODBC)
>> chan <- odbcConnect("MySQL51", uid="root", pwd="xxx")
>> first <- sqlQuery(chan, "select * from example")
>> close(chan)
>> First
>> #[1] pk id col1 col2
>> #<0 rows> (or 0-length row.names)
>>
>> ### This is the table I'm trying to save:
>> dframe <-data.frame(matrix(1:6,2,3))
>> colnames(dframe)=c("id","col1","col2")
>> dframe
>> # id col1 col2
>> #1 1 3 5
>> #2 2 4 6
>>
>> ### But this makes Rgui crash and close
>> chan <- odbcConnect("MySQL51", uid="root", pwd="xxx")
>> sqlSave(chan, dframe, tablename="example", rownames = FALSE, append=T)
>> close(chan)
>>
>> ### With rownames = T and safer=F, it works, but I loose the
>> autoincrementing PK in MySQL chan <- odbcConnect("MySQL51",
>> uid="root", pwd="momie") #default database=fbn
>> sqlSave(chan, dframe, tablename="example", rownames = T,
>> addPK=T,append=T,safer=F)
>> close(chan)
>>
>> Any idea?
>>
>> I'm on win2K, MySQL version 5.0.21-community-nt
> 
>>>I don't know why you're using DBI; perhaps it interferes with RODBC
> somehow.
> 
> **It still crashes without DBI
> 
>>>If that's not it, then you might want to try lower level methods than 
>>>sqlSave:  perhaps use sqlQuery to send an INSERT command to the 
>>>database.  Build up from there.
> 
> **Good suggestion, however, I'm not sure how to pass a table through an sql
> statement. From this archived doc,
> http://finzi.psych.upenn.edu/R/Rhelp02a/archive/10073.html I tried this
> using a dataframe instead of a single number.

You can't. You can only insert one record at a time this way in general, but MySQL allows multiple inserts on one line. So it's a lot of work, but you might figure out what's causing your crash.

> 
> But I get this error:
> 
> #test
> chan <- odbcConnect("MySQL51", uid="root", pwd="momie")  #default
> database=fbn
> query <- paste("INSERT INTO example VALUES ('",dframe,"')",sep="") 
> sqlQuery(chan,query) 
> close(chan)

You'd want something like

inserts <- with(dframe, paste("('", id, "','", col1, "','", col2, "')", sep="", collapse=",")
query <- paste("INSERT INTO example(id, col1, col2) VALUES", inserts) sqlQuery(chan, query)

(This isn't even tested to see if I got the syntax right, and it's probably not legal syntax on other databases. For those you could put together multiple INSERT statements.)

Duncan Murdoch

> [1] "[RODBC] ERROR: Could not SQLExecDirect"
> 
> [2] "S1T00 1136 [MySQL][ODBC 3.51 Driver][mysqld-5.0.21-community-nt]Column
> count doesn't match value count at row 1"
> 
>>>You might also want to look at the thread "Fast update of a lot of 
>>>records in a database?" from around May 20, though it was talking about 
>>>updates rather than insertions.
> 
> Duncan Murdoch
> 
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