public override ProjectionExpression GetQueryExpression(MappingEntity entity) { var tables = this.mapping.GetTables(entity); if (tables.Count <= 1) { return(base.GetQueryExpression(entity)); } var aliases = new Dictionary <string, TableAlias>(); MappingTable rootTable = tables.Single(ta => !this.mapping.IsExtensionTable(ta)); var tex = new TableExpression(new TableAlias(), entity, this.mapping.GetTableName(rootTable)); aliases.Add(this.mapping.GetAlias(rootTable), tex.Alias); Expression source = tex; foreach (MappingTable table in tables.Where(t => this.mapping.IsExtensionTable(t))) { TableAlias joinedTableAlias = new TableAlias(); string extensionAlias = this.mapping.GetAlias(table); aliases.Add(extensionAlias, joinedTableAlias); List <string> keyColumns = this.mapping.GetExtensionKeyColumnNames(table).ToList(); List <MemberInfo> relatedMembers = this.mapping.GetExtensionRelatedMembers(table).ToList(); string relatedAlias = this.mapping.GetExtensionRelatedAlias(table); TableAlias relatedTableAlias; aliases.TryGetValue(relatedAlias, out relatedTableAlias); TableExpression joinedTex = new TableExpression(joinedTableAlias, entity, this.mapping.GetTableName(table)); Expression cond = null; for (int i = 0, n = keyColumns.Count; i < n; i++) { var memberType = TypeHelper.GetMemberType(relatedMembers[i]); var colType = this.GetColumnType(entity, relatedMembers[i]); var relatedColumn = new ColumnExpression(memberType, colType, relatedTableAlias, this.mapping.GetColumnName(entity, relatedMembers[i])); var joinedColumn = new ColumnExpression(memberType, colType, joinedTableAlias, keyColumns[i]); var eq = joinedColumn.Equal(relatedColumn); cond = (cond != null) ? cond.And(eq) : eq; } source = new JoinExpression(JoinType.SingletonLeftOuter, source, joinedTex, cond); } var columns = new List <ColumnDeclaration>(); this.GetColumns(entity, aliases, columns); SelectExpression root = new SelectExpression(new TableAlias(), columns, source, null); var existingAliases = aliases.Values.ToArray(); Expression projector = this.GetEntityExpression(root, entity); var selectAlias = new TableAlias(); var pc = ColumnProjector.ProjectColumns(this.Translator.Linguist.Language, projector, null, selectAlias, root.Alias); var proj = new ProjectionExpression( new SelectExpression(selectAlias, pc.Columns, root, null), pc.Projector ); return((ProjectionExpression)this.Translator.Police.ApplyPolicy(proj, entity.ElementType)); }