edbColnames.RODBC_Excel: Retrieve column names of a table in a MS Excel file...

In easyrodbcexcel: Simple database interface for RODBC Excel.

Description

Retrieve column names of a table in a MS Excel file

(referenced by 'edb'). Wrapper around RODBC::sqlColumns().

Notice that the method does NOT retrieve the full table to

get its column names (so it should work even if the table is big).

Usage

## S3 method for class 'RODBC_Excel'
edbColnames(edb, tableName, onlyNames = TRUE, 


    testFiles = TRUE, ...)

Arguments

edb	An object of class 'edb', such as returned by edb.
tableName	Single character string. Name of the table to read in 'edb'.
onlyNames	Single logical. If TRUE only returns the column names (vector), and if FALSE returns a detailed table as in sqlColumns.
testFiles	Single logical. Should the function test for the presence (file.exist()) of the needed files in the folder before trying to fetch information from the database?
...	Additional parameters to be passed to dbListFields(). See ?dbListFields.

Value

The function returns a vector of character strings with the

columns / fields of the original MS Excel table, or a table with

full details on the columns (see onlyNames).

Author(s)

Julien MOEYS <[e-mail]>

See Also

edb, edbRead.RODBC_Excel,

edbWrite.RODBC_Excel,

edbNames.RODBC_Excel.

Examples

library( "easyrodbcexcel" ) 











# System check. Ingnore this or set 'testODBC' to TRUE 


testODBC <- (class(try(odbcDataSources())) != "try-error") & # Check (R)ODBC 


            (Sys.info()[[ "sysname" ]] == "Windows") &       # Only MS Windows


            (.Machine$"sizeof.pointer" == 4)                 # Only 32-bits 











### Windows only:


if( testODBC ){ 


    ### Make a copy of Excel example file:


    #   (a database of soil profile description) 


    file.copy( 


        from = system.file( "soils.xls", package = "easyrodbcexcel" ), 


        to   = "soils.xls" 


    )   


    


    # soils.xls is now in your working directory.


    


    


    


    library( "RODBC" ) # Because soils.db is a SQLite database...


    


    


    


    ### Describe the database (NB: this is not a connection)


    myDb <- edb( dbType = "RODBC_Excel", dbName = "soils.xls" ) 


    


    


    


    ### Use the database:


    


    # List the column names in a table:


    edbColnames( edb = myDb, tableName = "WRB_SOIL_GROUP" ) 


    


    


    


    ### Clean-up


    file.remove( "soils.xls" ) 


    


    


    


    ### Access 2007 ---------------------------------------------


    file.copy( 


        from = system.file( "soils.xlsx", package = "easyrodbcexcel" ), 


        to   = "soils.xlsx" 


    )   


    


    # soils.db is now in your working directory.


    


    


    


    library( "RODBC" ) # Because soils.db is a SQLite database...


    


    


    


    ### Describe the database (NB: this is not a connection)


    myDb2 <- edb( dbType = "RODBC_Excel", dbName = "soils.xlsx", 


        excelVersion = 2007 ) 


    


    


    


    ### Use the database:


    


    # List the column names in a table:


    edbColnames( edb = myDb2, tableName = "WRB_SOIL_GROUP" ) 


    


    


    


    ### Clean-up


    file.remove( "soils.xlsx" ) 


}   #

easyrodbcexcel documentation built on May 2, 2019, 6:12 p.m.