 evaluation an <a href="query_script_expressions.html">expression</a>.
The truth value of the expression determines whether code will branch, loop, break, etc.
</p>

<h3>EXAMPLES</h3>
<p>
Rebuild partitions for all NDB tables:
<blockquote><pre>
foreach($table, $schema, $engine: table like '%')
  if ($engine = 'ndbcluster')
    ALTER ONLINE TABLE :$schema.:$table REORGANIZE PARTITION;
</pre></blockquote>
</p>

<p>
Throttle deletion of rows:
<blockquote><pre>
while (DELETE FROM world.Country WHERE Continent =