digits from text:
<blockquote><pre>
set @txt := '12864xyz';
while(left(@txt,1) in ('0','1','2','3','4','5','6','7','8','9'))
  set @txt := substring(@txt, 2);
  
SELECT @txt;
  
+------+
| @txt |
+------+
| xyz  |
+------+  
</pre></blockquote>
</p>

<p>
<strong>DELETE</strong> statement as <i>expression</i>:
<blockquote><pre>
while (DELETE FROM world.Country WHERE Continent = 'Asia' LIMIT 10)
{
  -- We remove 10 rows at a time, and throttle by waiting in between 
  -- deletions twice the amount of time exe