title: RODBC Error - Cannot insert explicit value for identity column
body: <p>I'm trying to append records to an existing SQL table using the <code>sqlSave</code> method in the RODBC package.</p>
  
  <pre><code>df &lt;- data.frame(EmployeeID = c(NA, NA, NA), EmployeeName=c("Bob", "Sue", "Jane"))
  
  sqlSave(myconn, dat=df, tablename = "Employees", append = TRUE, rownames = FALSE, colnames = FALSE, verbose = TRUE, safer = TRUE, 
          addPK = FALSE, typeInfo, varTypes, fast = TRUE, test = FALSE, nastring = NULL)
  </code></pre>
  
  <p>However, I keep getting the error </p>
  
  <p><em>[RODBC] Failed exec in Update
  23000 544 [Microsoft][ODBC SQL Server Driver][SQL Server]Cannot insert explicit value for identity column in table 'Employees' when IDENTITY_INSERT is set to OFF.</em></p>
  
  <p>My table should be creating IDs automatically.  What gives?</p>