Index: trunk/core/kernel/utility/unit_config_reader.php
===================================================================
diff -u -N -r8015 -r8029
--- trunk/core/kernel/utility/unit_config_reader.php	(.../unit_config_reader.php)	(revision 8015)
+++ trunk/core/kernel/utility/unit_config_reader.php	(.../unit_config_reader.php)	(revision 8029)
@@ -381,6 +381,7 @@
 			'default_missing' => 'Default value for field <strong>%s</strong> not set in config',
 			'not_null_error1' => 'Field <strong>%s</strong> is NOT NULL in the database, but is not configured as not_null or required',
 			'not_null_error2' => 'Field <strong>%s</strong> is described as NOT NULL in config, but <strong>does not have DEFAULT value</strong>',
+			'not_null_error3' => 'Field <strong>%s</strong> is described as <strong>NOT NULL in config</strong>, but is <strong>NULL in db</strong>',
 			'invalid_default' => '<strong>Default value</strong> for field %s<strong>%s</strong> not sync. to db (in config = %s, in db = %s)',
 			'type_missing' => '<strong>Type definition</strong> for field <strong>%s</strong> missing in config',
 		);
@@ -413,21 +414,26 @@
 					}
 					
 					if ($field['Null'] != 'YES') {
-						// MySQL5 for null returns "NO", but MySQL4 returns ""
+						// field is NOT NULL in database (MySQL5 for null returns "NO", but MySQL4 returns "")
 						if ( $f_name != $config['IDField'] && !isset($options['not_null']) && !isset($options['required']) ) {
 							$config_errors[] = sprintf($error_messages['not_null_error1'], $f_name);
 						}
-						if ( isset($options['not_null']) && !isset($options['default']) ) {
+						if (isset($options['not_null']) && $options['not_null'] && !isset($options['default']) ) {
 							$config_errors[] = sprintf($error_messages['not_null_error2'], $f_name);
 						}
 					}
+					else {
+						if (isset($options['not_null']) && $options['not_null']) {
+							$config_errors[] = sprintf($error_messages['not_null_error3'], $f_name);
+						}					
+					}
 
 					if (!array_key_exists('type', $options)) {
 						$config_errors[] = sprintf($error_messages['type_missing'], $f_name);
 					}
 					
 					if (!$default_missing) {
-						if ($f_name == $config['IDField'] && $options['default'] !== 0) {
+						if ($f_name == $config['IDField'] && $options['type'] != 'string' && $options['default'] !== 0) {
 							$config_errors[] = sprintf($error_messages['invalid_default'], '<span class="debug_error">IDField</span> ', $f_name, $this->varDump($options['default']), $this->varDump($field['Default']));
 						}
 						else if ($options['default'] != '#NOW#' && $field['Default'] !== $options['default'] && !in_array($options['type'], $float_types)) {