从R向Access ODBC数据库中的现有表添加新列

Question

I am trying to add a new column to an existing table in access using R.

I cannot figure out the way to do it. This is what I tried:

install.packages("RODBC")
require(RODBC)

channel <- odbcConnect("Access01", believeNRows=FALSE)
df <- sqlFetch(channel, "Customers")
df

 ID Last_Name First_Name  Email_Address Business_Phone Home_Phone Mobile_Phone Fax_Number        Address
1  1       Sam      Marty  mlast@123.com     7771234567 8882626262   9998283838 5551717171   123 Main St.
2  2       Sam      Sally sfirst@123.com     5557778888 5558889999   5559991111 5552223333 234 Second Ave
      City State_Province ZIP_Postal_Code Country_Region Sex Date_of_birth
1 Anywhere             ST           55555            USA   M    1960-02-03
2   guirao             ST           22222            USA   f    1975-12-12


df <- cbind(df, test=c("A", "B")
df

 ID Last_Name First_Name  Email_Address Business_Phone Home_Phone Mobile_Phone Fax_Number        Address
1  1       Sam      Marty  mlast@123.com     7771234567 8882626262   9998283838 5551717171   123 Main St.
2  2       Sam      Sally sfirst@123.com     5557778888 5558889999   5559991111 5552223333 234 Second Ave
      City State_Province ZIP_Postal_Code Country_Region Sex Date_of_birth test
1 Anywhere             ST           55555            USA   M    1960-02-03    A
2   guirao             ST           22222            USA   f    1975-12-12    B


sqlUpdate(channel, df, tablename = "Customers", index="ID")

**Error in sqlUpdate(channel, df, tablename = "Customers", index = "ID") : 
  data frame column(s) test not in database table**

I also tried to use the sqlSave command but as far as I know it just let you append new rows. Is it a database structure problem or am I doing something wrong with the R commands?

Thanks in advance.

Answer 1

It looks like sqlUpdate() does not alter the structure of the table automatically (not that I would expect it to). So, you'll probably have to so something like

sqlQuery(channel, 'ALTER TABLE Customers ADD COLUMN test TEXT(1)')

before you try to apply the update.