title: sqlUpdate returns error "[RODBC] Failed exec in Update" when updating table read from DB
body: <p>I'm creating a table and writing it to a database with RODBC. No problems.</p>
  
  <p>First I tried updating the table in R and writing the updates back line by line using sqlUpdate in the same R script and the same R session as initialising it. No problems.</p>
  
  <p>But when I try to split this into two scripts (one to initialise the table and one to read it back into R, calculate updates and write the updates to the database), I get the following error (the import and updates work fine, it's just writing it back to the DB that fails):</p>
  
  <pre><code>[RODBC] Failed exec in Update
  </code></pre>
  
  <p>The code I use to update is the following (which worked when the table was in my R session and the initialisation and the updates were in the same script):</p>
  
  <pre><code>conOut &lt;- odbcConnect("myDB", uid = "myID", pwd = "myPwd", believeNRows = T)
  
  sqlUpdate(conOut, myTable)
  
  odbcClose(conOut)
  </code></pre>
  
  <p>Am I just missing something really obvious like the table being converted to a wrong format when it is imported from the database? Or is there something else I can do to make it work?</p>
  
  <p>Cheers.</p>