title: Insert Base64Encoded string returns Incorrect string value (MySQL)
body: <p>I'm trying to insert a Base64Encoded string and sometimes it returns me the MySQL error: <code>Incorrect string value: '\xFBy\x1Eh\x00...' for column 'Data' at row 1 (error code: 1366, State: HY000)</code></p>
  
  <p>The query I run is simple, like:</p>
  
  <pre><code>UPDATE Table SET Data='BASE64ENCODED STRING'
  </code></pre>
  
  <p>Important to note however is that the incorrect string value error does not always occur. If I repeat the exact same query again, it accepts the string...?</p>
  
  <p>The <code>Data-column</code> is of type <code>LONGTEXT</code> and has the <code>utf8mb4_general_ci</code> collation.</p>
  
  <p>The <code>connection</code> is also using the <code>utf8mb4</code> character set with <code>utf8mb4_general_ci</code> collation.</p>
  
  <p>What am I doing wrong and how is it possible that when I run the exact same query again, it doesn't throw the error and inserts (updates) the value?</p>
  
  <p>I have already checked the base64 encoded string, which does not contain a string like: <code>\xFBy\x1Eh\x00</code></p>
  
  <p><em>I use prepared statements in order to execute the update</em></p>