title: Sqlite replace issue when I try to update
body: <p>I have this SQL query</p>
  
  <p>bd.replace(TABLE,null,cv);</p>
  
  <p>where cv is {_id=1,column1=x,column3=z}; // note there is no column2</p>
  
  <p>the TABLE has the follow scheme:</p>
  
  <p>_id (as a PRIMARY KEY)| column1 (as TEXT)| column2 (as TEXT)| column3 (as TEXT)</p>
  
  <p>before I run the query I have already the register _id=1 with the following values(_id=1,column1=a,column2=b,column3=c) so after it runs the query I get that 
  (_id=1,column1=x,column2=null,column3=z)   why didn't it keep the column2 to b? </p>
  
  <p>¿does anybody  know  how to keep this values as it was before?    </p>
  
  <p>IMPORTANT : I use replace becouse I need to insert a new row in case it doesn't exist.</p>
  
  <p>THANKS in advance </p>