title: Merge CSV data into existing table
body: <p>I want to merge data from CSV into an already existing table that has data:</p>
  
  <p>The table I already have has 4 columns, 2 of which are NULL. My CSV file has 3 columns: one is the Primary Key to be used to match the table and the other 2 have information to fill my already-existing table.</p>
  
  <p>I want to be able to match the CSV's Primary Key to my table's Primary Key, and insert the information from the CSV into the matched row.</p>
  
  <p>My table goes something like:</p>
  
  <pre><code>+--------+----------------+------+
  | CardID | Topic | Number | Date |
  +--------+----------------+------+
   pk00001 | name  | NULL   | NULL |
  +--------+----------------+------+
  </code></pre>
  
  <p>Whereas the CSV goes like:</p>
  
  <pre><code>"ID","Number","Date"
  "pk00001","100001","1999/01/01"
  </code></pre>
  
  <p>The table doesn't have any constraints: it's all <code>VARCHAR(256)</code></p>
  
  <p>However, my table has more rows than the CSV, and the operation shouldn't touch those rows.</p>
  
  <p>Is it possible to create such a query in MySQL?</p>