====== lmbSQLFieldCriteria ======

lmbSQLFieldCriteria creates a simple condition for a db table field.

lmbSQLFieldCriteria accepts field name, value and condition type in constructor:
<code php>
$criteria = new lmbSQLFieldCriteria('contract.start_date', $date_str, lmbSQLFieldCriteria:: LESS);
$criteria = new lmbSQLFieldCriteria('contract.end_date', $date_str, '>');
</code>

Here is the list of available condition types:
  * EQUAL = "=";
  * NOT_EQUAL = "<>";
  * GREATER = ">";
  * LESS = " < ";
  * GREATER_EQUAL = " >= ";
  * LESS_EQUAL = " <= ";
  * LIKE = " LIKE ";
  * NOT_LIKE = " NOT LIKE ";
  * IN = " IN ";
  * NOT_IN = " NOT IN ";
  * ISNULL = " IS NULL";
  * ISNOTNULL = " IS NOT NULL";