title: why is r/sqlite requiring a primary key?
body: <p>so i have a table that was created using:</p>
  
  <pre><code>dbGetQuery(conn, "CREATE TABLE Data (DataID integer primary key autoincrement, 
             DataTypeID integer, DataName varchar)")
  </code></pre>
  
  <p>after some code, i create a data frame called "insertdata" that is like this:</p>
  
  <pre><code>    type    name
  1   1   Data1
  2   1   Data2
  3   1   Data3
  4   1   Data4
  5   1   Data5
  </code></pre>
  
  <p>and i use the following to insert it into my table:</p>
  
  <pre><code>dbWriteTable(conn, "Data", insertdata, append=TRUE)
  </code></pre>
  
  <p>later on i create another dataframe to insert of a different type, like this:</p>
  
  <pre><code>    type    name
  1   2   OtherData1
  2   2   OtherData2
  3   2   OtherData3
  4   2   OtherData4
  5   2   OtherData5
  </code></pre>
  
  <p>but when i use the same dbWriteTable as before, it tells me </p>
  
  <pre><code>"Warning message:
  In value[[3L]](cond) :
    RS-DBI driver: (RS_SQLite_exec: could not execute: PRIMARY KEY must be unique)"
  </code></pre>
  
  <p>Why is that?  My table is set to auto-increment the primary key.  I don't understand where the non-unique characters would be coming from.  Is it because the rownames are the same in each?  </p>