title: Cancel a transaction or part of a transaction before commit?
body: <p>I have a long transaction that I have began using <code>BEGIN</code>, and I made a mistake about 3 lines prior to the last line.  Is there a way to null that line?</p>
  
  <p>Here's an example:</p>
  
  <pre><code>BEGIN TRANSACTION;
  CREATE TABLE purchase(id integer PRIMARY KEY, purchasePrice integer CHECK(purchasePrice&gt;0), customer text);
  INSERT INTO purchase(purchasePrice, customer) VALUES(1200, "Jerome");
  INSERT INTO purchase(purchasePrice, customer) VALUES(200, "Jeffery");
  INSERT INTO purchase(purchasePrice, customer) VALUES(40, "Craig");
  INSERT INTO purchase(purchasePrice, customer) VALUES(1640, "Donovan");
  INSERT INTO purchase(purchasePrice, customer) VALUES(100, "Williams");
  INSERT INTO purchase(purchasePrice, customer) VALUES(50, "Matsushi");
  INSERT INTO purchase(purchasePrice, customer) VALUES(150, "Xhao");
  INSERT INTO purchase(purchasePrice, customer) VALUES(250, "Dilberta");
  INSERT INTO purchase(purchasePrice, customer) VALUES(840, "Brow"); //Supposed to be 9440,"Brown"
  INSERT INTO purchase(purchasePrice, customer) VALUES(440, "DarkBrown");
  INSERT INTO purchase(purchasePrice, customer) VALUES(20, "Black");
  COMMIT;
  </code></pre>
  
  <p>I do understand that I can later update the affected row.</p>
  
  <p>Another example situation:</p>
  
  <pre><code>BEGIN TRANSACTION;
  CREATE TABLE Movies(MId integer primary key autoincrement, Title text);
  INSERT INTO Movies VALUES(1,'Capote');
  INSERT INTO Movies VALUES(2,'Scent of a woman');
  INSERT INTO Movies VALUES(3,'Stigmata');
  INSERT INTO Movies VALUES(4,'Exorcist');
  INSERT INTO Movies VALUES(5,'Hamsun');
  //Changed my mind and want to name the table "movie" and  name the columns "m_id" and "title".
  </code></pre>
  
  <p>So, I'm wondering a) how to cancel; and b) is it possible to go up a few lines, and if so, how?</p>