[R] odbcConnectExcel2007 creates corrupted files

[Mark Lyman]

I tried creating a .xlsx file using odbcConnectExcel2007 and adding a 
worksheet with sqlSave. This seems to work, I am even able to query the 
worksheet, but when I try opening the file in Excel I get the following 
message: "Excel cannot open the file 'test.xlx' because the file format or 
file extension is not valid. Verify that the file has not been corrupted and 
that the file extension matches the format of the file." Is this a known 
issue? Or just user error? The RODBC manual seemed to indicate that sqlSave 
worked fine with Excel, however it did not mention Excel 2007.

I am running Excel 2007 and R 2.12.1 on Windows XP. Below is my example code. 

$ library(RODBC)
$ 
$ # This doesn't work
$ # Connect to an previously non-existent Excel file
$ out <- odbcConnectExcel2007("test.xlsx", readOnly=FALSE)
$ test <- data.frame(x=1:10, y=rnorm(10))
$ sqlSave(out, test)
$ sqlTables(out)
                                                    TABLE_CAT TABLE_SCHEM 
TABLE_NAME   TABLE_TYPE REMARKS
1 C:\\Documents and Settings\\G69974\\My Documents\\test.xlsx        <NA>      
test$ SYSTEM TABLE    <NA>
2 C:\\Documents and Settings\\G69974\\My Documents\\test.xlsx        
<NA>       test        TABLE    <NA>
$ sqlFetch(out, "test")
    x          y
1   1  0.5832882
2   2  0.4387569
3   3 -0.6444048
4   4 -1.0013450
5   5  1.0324718
6   6 -0.7844128
7   7 -1.6789266
8   8  0.1402672
9   9  0.8650061
10 10 -0.0420201
$ close(out)
$ # Opening test.xlsx now fails
$ 
$ # This works
$ out <- odbcConnectExcel("test.xls", readOnly=FALSE)
$ test <- data.frame(x=1:10, y=rnorm(10))
$ sqlSave(out, test)
$ sqlTables(out)
                                               TABLE_CAT TABLE_SCHEM 
TABLE_NAME   TABLE_TYPE REMARKS
1 C:\\Documents and Settings\\G69974\\My Documents\\test        <NA>      
test$ SYSTEM TABLE    <NA>
2 C:\\Documents and Settings\\G69974\\My Documents\\test        <NA>       
test        TABLE    <NA>
$ sqlFetch(out, "test")
    x          y
1   1  0.5955787
2   2  1.0517528
3   3  0.3884892
4   4 -2.1408813
5   5 -0.7081686
6   6  0.1511828
7   7  2.0560555
8   8 -0.5801912
9   9 -0.6988058
10 10 -0.1237739
$ close(out)
$ # Opening test.xls now works