diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
index 9ec0c1374..e8018b6d4 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/OrderElement.java
@@ -108,7 +108,7 @@ public abstract class OrderElement extends IntegrationEntity implements
 
     private Boolean dirtyLastAdvanceMeasurementForSpreading = true;
 
-    private SumChargedEffort sumChargedEffort = SumChargedEffort.create();
+    private SumChargedEffort sumChargedEffort;
 
     public OrderElementTemplate getTemplate() {
         return template;
diff --git a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/SumChargedEffort.java b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/SumChargedEffort.java
index bbb782ec9..e23b89689 100644
--- a/libreplan-business/src/main/java/org/libreplan/business/orders/entities/SumChargedEffort.java
+++ b/libreplan-business/src/main/java/org/libreplan/business/orders/entities/SumChargedEffort.java
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2009-2010 Fundación para o Fomento da Calidade Industrial e
  *                         Desenvolvemento Tecnolóxico de Galicia
- * Copyright (C) 2010-2011 Igalia, S.L.
+ * Copyright (C) 2010-2012 Igalia, S.L.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
@@ -33,6 +33,8 @@ import org.libreplan.business.workingday.EffortDuration;
  */
 public class SumChargedEffort extends BaseEntity {
 
+    private OrderElement orderElement;
+
     private EffortDuration directChargedEffort = EffortDuration.zero();
 
     private EffortDuration indirectChargedEffort = EffortDuration.zero();
@@ -43,6 +45,10 @@ public class SumChargedEffort extends BaseEntity {
         return create(new SumChargedEffort());
     }
 
+    public OrderElement getOrderElement() {
+        return orderElement;
+    }
+
     public void addDirectChargedEffort(EffortDuration directChargedEffort) {
         this.directChargedEffort = this.directChargedEffort
                 .plus(directChargedEffort);
diff --git a/libreplan-business/src/main/resources/db.changelog-1.2.xml b/libreplan-business/src/main/resources/db.changelog-1.2.xml
index faec5121f..368f1ea96 100644
--- a/libreplan-business/src/main/resources/db.changelog-1.2.xml
+++ b/libreplan-business/src/main/resources/db.changelog-1.2.xml
@@ -92,4 +92,81 @@
             columnName="budget" defaultValueNumeric="0" />
     </changeSet>
 
+    <changeSet id="change-mapping-order-element-and-sum-charged-effort-postgresql"
+        author="mrego">
+        <preConditions onFail="MARK_RAN">
+            <dbms type="postgresql" />
+        </preConditions>
+        <comment>Change mapping between OrderElement and SumChargedEffort in MySQL</comment>
+
+        <addColumn tableName="sum_charged_effort">
+            <column name="order_element" type="BIGINT" />
+        </addColumn>
+        <createProcedure>
+            CREATE OR REPLACE FUNCTION chageMappingBetweenOrderElementAndSumChargedEffort() RETURNS VOID AS $$
+            DECLARE
+                sce RECORD;
+            BEGIN
+                FOR sce IN SELECT sum_charged_effort_id AS id FROM order_element
+                LOOP
+                    EXECUTE 'UPDATE sum_charged_effort '
+                        || 'SET order_element '
+                        || ' = (SELECT id FROM order_element '
+                            || 'WHERE sum_charged_effort_id '
+                            || ' = '
+                            || quote_literal(sce.id)
+                            || ') '
+                        || 'WHERE id '
+                        || ' = '
+                        || quote_literal(sce.id);
+                END LOOP;
+            END;
+            $$ LANGUAGE plpgsql;
+        </createProcedure>
+        <sql>SELECT chageMappingBetweenOrderElementAndSumChargedEffort()</sql>
+        <addForeignKeyConstraint constraintName="sum_charged_effort_order_element_fkey"
+            baseTableName="sum_charged_effort" baseColumnNames="order_element"
+            referencedTableName="order_element" referencedColumnNames="id" />
+        <dropColumn tableName="order_element" columnName="sum_charged_effort_id"/>
+    </changeSet>
+
+    <changeSet id="change-mapping-order-element-and-sum-charged-effort-mysql"
+        author="mrego">
+        <preConditions onFail="MARK_RAN">
+            <dbms type="mysql" />
+        </preConditions>
+        <comment>Change mapping between OrderElement and SumChargedEffort in PostgreSQL</comment>
+
+        <addColumn tableName="sum_charged_effort">
+            <column name="order_element" type="BIGINT" />
+        </addColumn>
+        <sql>DROP PROCEDURE IF EXISTS chageMappingBetweenOrderElementAndSumChargedEffort</sql>
+        <sql splitStatements="false">
+            CREATE PROCEDURE chageMappingBetweenOrderElementAndSumChargedEffort()
+            BEGIN
+                DECLARE done INT DEFAULT FALSE;
+                DECLARE sce_id INT;
+                DECLARE cursor_sce_ids CURSOR FOR SELECT sum_charged_effort_id AS id FROM order_element;
+                DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
+
+                OPEN cursor_sce_ids;
+
+                ids_loop: LOOP
+                    FETCH cursor_sce_ids INTO sce_id;
+                    IF done THEN
+                        LEAVE ids_loop;
+                    END IF;
+                    UPDATE sum_charged_effort SET order_element = (SELECT id FROM order_element WHERE sum_charged_effort_id = sce_id) WHERE id = sce_id;
+                END LOOP;
+
+                CLOSE cursor_sce_ids;
+            END;
+        </sql>
+        <sql>CALL chageMappingBetweenOrderElementAndSumChargedEffort()</sql>
+        <addForeignKeyConstraint constraintName="sum_charged_effort_order_element_fkey"
+            baseTableName="sum_charged_effort" baseColumnNames="order_element"
+            referencedTableName="order_element" referencedColumnNames="id" />
+        <dropColumn tableName="order_element" columnName="sum_charged_effort_id"/>
+    </changeSet>
+
 </databaseChangeLog>
diff --git a/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml b/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
index 380863f58..d1ada6218 100644
--- a/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
+++ b/libreplan-business/src/main/resources/org/libreplan/business/orders/entities/Orders.hbm.xml
@@ -74,12 +74,8 @@
                 column="scheduling_state_for_version_id" />
         </map>
 
-       <many-to-one name="sumChargedEffort"
-           class="SumChargedEffort"
-           column="sum_charged_effort_id"
-           cascade="save-update, delete"
-           unique="true"
-           lazy="false" />
+        <one-to-one name="sumChargedEffort" class="SumChargedEffort"
+            cascade="delete" property-ref="orderElement" />
 
         <joined-subclass name="OrderLineGroup"  table="order_line_group">
             <key column="order_element_id"></key>
@@ -246,6 +242,9 @@
         </id>
         <version name="version" access="property" type="long" />
 
+        <many-to-one name="orderElement" column="order_element"
+            class="OrderElement" cascade="none" unique="true" />
+
         <property name="directChargedEffort" access="field"
             column="direct_charged_effort"
             type="org.libreplan.business.workingday.hibernate.EffortDurationType" />