Index: typo3/sysext/dbal/class.ux_t3lib_db.php
===================================================================
--- typo3/sysext/dbal/class.ux_t3lib_db.php	(revision 5387)
+++ typo3/sysext/dbal/class.ux_t3lib_db.php	(working copy)
@@ -2406,12 +2406,22 @@
 
 						// do we have a field name in the value?
 						// this is a very simplistic check, beware
-					if(is_array($this->mapping[$t]['mapFieldNames']) && (!is_numeric($sqlPartArray[$k]['value'][0]) && !isset($sqlPartArray[$k]['value'][1]))) {
+					if (!is_numeric($sqlPartArray[$k]['value'][0]) && !isset($sqlPartArray[$k]['value'][1])) {
 						$fieldArray = explode('.', $sqlPartArray[$k]['value'][0]);
-						if(count($fieldArray)==1 && isset($this->mapping[$t]['mapFieldNames'][$fieldArray[0]])) {
+						if (count($fieldArray) == 1 && is_array($this->mapping[$t]['mapFieldNames']) && isset($this->mapping[$t]['mapFieldNames'][$fieldArray[0]])) {
 							$sqlPartArray[$k]['value'][0] = $this->mapping[$t]['mapFieldNames'][$fieldArray[0]];
-						} elseif(count($fieldArray)==2 && isset($this->mapping[$t]['mapFieldNames'][$fieldArray[1]])) {
-							$sqlPartArray[$k]['value'][0] = $fieldArray[0].'.'.$this->mapping[$t]['mapFieldNames'][$fieldArray[1]];
+						} elseif (count($fieldArray) == 2) {
+								// Map the external table
+							$table = $fieldArray[0];
+							if (isset($this->mapping[$fieldArray[0]]['mapTableName'])) {
+								$table = $this->mapping[$fieldArray[0]]['mapTableName'];
+							}
+								// Map the field itself
+							$field = $fieldArray[1];
+							if (is_array($this->mapping[$fieldArray[0]]['mapFieldNames']) && isset($this->mapping[$fieldArray[0]]['mapFieldNames'][$fieldArray[1]])) {
+								$field = $this->mapping[$fieldArray[0]]['mapFieldNames'][$fieldArray[1]];
+							}
+							$sqlPartArray[$k]['value'][0] = $table . '.' . $field;
 						}
 					}