title: Android SQLite: nullColumnHack parameter in insert/replace methods
body: <p>The Android SDK has some convenience methods for manipulating data with SQLite.  However both the <a href="http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#insert%28java.lang.String,%20java.lang.String,%20android.content.ContentValues%29" rel="noreferrer">insert</a> and <a href="http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#replace%28java.lang.String,%20java.lang.String,%20android.content.ContentValues%29" rel="noreferrer">replace</a> methods use some <code>nullColumnHack</code> parameter which usage I don't understand.</p>
  
  <p>The documentation explains it with the following, but what if a table has multiple columns that allow <code>NULL</code>? I really don't get it :/</p>
  
  <blockquote>
    <p>SQL doesn't allow inserting a completely empty row, so if initialValues is empty, this column [<em>/row for replace</em>] will explicitly be assigned a <code>NULL</code> value.</p>
  </blockquote>