C# QueryBuilder.OrderBy方法代码示例

        /// <summary>
        /// Gets all the sub-namespaces.
        /// </summary>
        /// <returns>The sub-namespaces, sorted by name.</returns>
        public NamespaceInfo[] GetNamespaces()
        {
            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            // select ... from Namespace left join Page on Namespace.DefaultPage = Page.Name where Namespace.Name <> '' and (Namespace.DefaultPage is null or Page.Namespace <> '')
            string query = queryBuilder.SelectFrom("Namespace", "Page", "DefaultPage", "Name", Join.LeftJoin, new string[] { "Name", "DefaultPage" }, new string[] { "CreationDateTime" });
            query = queryBuilder.Where(query, "Namespace", "Name", WhereOperator.NotEquals, "Empty1");
            query = queryBuilder.AndWhere(query, "Namespace", "DefaultPage", WhereOperator.IsNull, null, true, false);
            query = queryBuilder.OrWhere(query, "Page", "Namespace", WhereOperator.NotEquals, "Empty2", false, true);
            query = queryBuilder.OrderBy(query, new[] { "Namespace_Name" }, new[] { Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(2);
            parameters.Add(new Parameter(ParameterType.String, "Empty1", ""));
            parameters.Add(new Parameter(ParameterType.String, "Empty2", ""));

            DbCommand command = builder.GetCommand(connString, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<NamespaceInfo> result = new List<NamespaceInfo>(10);

                while(reader.Read()) {
                    string realName = reader["Namespace_Name"] as string;
                    string page = GetNullableColumn<string>(reader, "Namespace_DefaultPage", null);
                    PageInfo defaultPage = string.IsNullOrEmpty(page) ? null :
                        new PageInfo(NameTools.GetFullName(realName, page), this, (DateTime)reader["Page_CreationDateTime"]);

                    // The query returns duplicate entries if the main page of two or more namespaces have the same name
                    if(result.Find(n => { return n.Name.Equals(realName); }) == null) {
                        result.Add(new NamespaceInfo(realName, this, defaultPage));
                    }
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets all the Navigation Paths in a Namespace.
        /// </summary>
        /// <param name="nspace">The Namespace.</param>
        /// <returns>All the Navigation Paths, sorted by name.</returns>
        public NavigationPath[] GetNavigationPaths(NamespaceInfo nspace)
        {
            string nspaceName = nspace != null ? nspace.Name : "";

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("NavigationPath", new string[] { "Name", "Namespace", "Page" });
            query = queryBuilder.Where(query, "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.OrderBy(query, new string[] { "Namespace", "Name", "Number" }, new Ordering[] { Ordering.Asc, Ordering.Asc, Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspaceName));

            DbCommand command = builder.GetCommand(connString, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<NavigationPath> result = new List<NavigationPath>(10);

                string prevName = "|||";
                string name;
                string actualNamespace = "";
                List<string> pages = new List<string>(10);

                while(reader.Read()) {
                    name = reader["Name"] as string;

                    if(name != prevName) {
                        actualNamespace = reader["Namespace"] as string;

                        if(prevName != "|||") {
                            result[result.Count - 1].Pages = pages.ToArray();
                            pages.Clear();
                        }

                        result.Add(new NavigationPath(NameTools.GetFullName(actualNamespace, name), this));
                    }

                    prevName = name;
                    pages.Add(NameTools.GetFullName(actualNamespace, reader["Page"] as string));
                }

                if(result.Count > 0) {
                    result[result.Count - 1].Pages = pages.ToArray();
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets all the Pages in a namespace.
        /// </summary>
        /// <param name="connection">A database connection.</param>
        /// <param name="nspace">The namespace (<c>null</c> for the root).</param>
        /// <returns>All the Pages in the namespace. The array is not sorted.</returns>
        private PageInfo[] GetPages(DbConnection connection, NamespaceInfo nspace)
        {
            string nspaceName = nspace != null ? nspace.Name : "";

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Page");
            query = queryBuilder.Where(query, "Namespace", WhereOperator.Equals, "Namespace");

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspaceName));
            query = queryBuilder.OrderBy(query, new[] { "Name" }, new[] { Ordering.Asc });

            DbCommand command = builder.GetCommand(connection, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<PageInfo> result = new List<PageInfo>(100);

                while(reader.Read()) {
                    result.Add(new PageInfo(NameTools.GetFullName(reader["Namespace"] as string, reader["Name"] as string),
                        this, (DateTime)reader["CreationDateTime"]));
                }

                CloseReader(reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets all the categories of a page.
        /// </summary>
        /// <param name="page">The page.</param>
        /// <returns>The categories, sorted by name.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="page"/> is <c>null</c>.</exception>
        public CategoryInfo[] GetCategoriesForPage(PageInfo page)
        {
            if(page == null) throw new ArgumentNullException("page");

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string nspace, pageName;
            NameTools.ExpandFullName(page.FullName, out nspace, out pageName);
            if(nspace == null) nspace = "";

            string query = queryBuilder.SelectFrom("Category", "CategoryBinding", new string[] { "Name", "Namespace" }, new string[] { "Category", "Namespace" }, Join.LeftJoin,
                new string[] { "Name", "Namespace" }, new string[] { "Page" });
            query = queryBuilder.Where(query, "CategoryBinding", "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.AndWhere(query, "CategoryBinding", "Page", WhereOperator.Equals, "Page");
            query = queryBuilder.OrderBy(query, new[] { "Category_Name" }, new[] { Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(2);
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
            parameters.Add(new Parameter(ParameterType.String, "Page", pageName));

            DbCommand command = builder.GetCommand(connString, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<CategoryInfo> result = new List<CategoryInfo>(20);
                List<string> pages = new List<string>(50);

                string prevName = "|||";
                string name = null;

                while(reader.Read()) {
                    name = reader["Category_Name"] as string;

                    if(name != prevName) {
                        if(prevName != "|||") {
                            result[result.Count - 1].Pages = pages.ToArray();
                            pages.Clear();
                        }

                        result.Add(new CategoryInfo(NameTools.GetFullName(reader["Category_Namespace"] as string, name), this));
                    }

                    prevName = name;
                    if(!IsDBNull(reader, "CategoryBinding_Page")) {
                        pages.Add(NameTools.GetFullName(reader["Category_Namespace"] as string, reader["CategoryBinding_Page"] as string));
                    }
                }

                CloseReader(command, reader);

                if(result.Count > 0) result[result.Count - 1].Pages = pages.ToArray();

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets the user groups of a user.
        /// </summary>
        /// <param name="transaction">A database transaction.</param>
        /// <param name="username">The username.</param>
        /// <returns>The groups.</returns>
        private string[] GetUserGroups(DbTransaction transaction, string username)
        {
            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("UserGroupMembership", new string[] { "UserGroup" });
            query = queryBuilder.Where(query, "User", WhereOperator.Equals, "Username");
            queryBuilder.OrderBy(query, new[] { "UserGroup_Name" }, new[] { Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Username", username));

            DbCommand command = builder.GetCommand(transaction, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<string> result = new List<string>(5);

                while(reader.Read()) {
                    result.Add(reader["UserGroup"] as string);
                }

                CloseReader(reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets the Page Messages.
        /// </summary>
        /// <param name="connection">A database connection.</param>
        /// <param name="page">The Page.</param>
        /// <returns>The list of the <b>first-level</b> Messages, containing the replies properly nested, sorted by date/time.</returns>
        private Message[] GetMessages(DbConnection connection, PageInfo page)
        {
            if(GetPage(connection, page.FullName) == null) return null;

            // 1. Load all messages in memory in a dictionary id->message
            // 2. Build tree using ParentID

            string nspace, name;
            NameTools.ExpandFullName(page.FullName, out nspace, out name);
            if(nspace == null) nspace = "";

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Message", new string[] { "Id", "Parent", "Username", "Subject", "DateTime", "Body" });
            query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
            query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.OrderBy(query, new string[] { "DateTime", "Id" }, new Ordering[] { Ordering.Asc, Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(2);
            parameters.Add(new Parameter(ParameterType.String, "Page", name));
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));

            DbCommand command = builder.GetCommand(connection, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                Dictionary<short, Message> allMessages = new Dictionary<short, Message>(50);
                List<short> ids = new List<short>(50);
                List<short?> parents = new List<short?>(50);

                while(reader.Read()) {
                    Message msg = new Message((short)reader["Id"], reader["Username"] as string, reader["Subject"] as string,
                        (DateTime)reader["DateTime"], reader["Body"] as string);

                    ids.Add((short)msg.ID);

                    // Import from V2: parent = -1, otherwise null
                    if(!IsDBNull(reader, "Parent")) {
                        short par = (short)reader["Parent"];
                        if(par >= 0) parents.Add(par);
                        else parents.Add(null);
                    }
                    else parents.Add(null);

                    allMessages.Add((short)msg.ID, msg);
                }

                CloseReader(reader);

                // Add messages to their parents and build the top-level messages list
                List<Message> result = new List<Message>(20);

                for(int i = 0; i < ids.Count; i++) {
                    short? currentParent = parents[i];
                    short currentId = ids[i];

                    if(currentParent.HasValue) {
                        List<Message> replies = new List<Message>(allMessages[currentParent.Value].Replies);
                        replies.Add(allMessages[currentId]);
                        allMessages[currentParent.Value].Replies = replies.ToArray();
                    }
                    else result.Add(allMessages[currentId]);
                }

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets the Backup/Revision numbers of a Page.
        /// </summary>
        /// <param name="connection">A database connection.</param>
        /// <param name="page">The Page to get the Backups of.</param>
        /// <returns>The Backup/Revision numbers.</returns>
        private int[] GetBackups(DbConnection connection, PageInfo page)
        {
            if(GetPage(connection, page.FullName) == null) {
                return null;
            }

            string name, nspace;
            NameTools.ExpandFullName(page.FullName, out nspace, out name);
            if(nspace == null) nspace = "";

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("PageContent", new string[] { "Revision" });
            query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
            query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.AndWhere(query, "Revision", WhereOperator.GreaterThanOrEqualTo, "Revision");
            query = queryBuilder.OrderBy(query, new[] { "Revision" }, new[] { Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(3);
            parameters.Add(new Parameter(ParameterType.String, "Page", name));
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
            parameters.Add(new Parameter(ParameterType.Int16, "Revision", FirstRevision));

            DbCommand command = builder.GetCommand(connection, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<int> result = new List<int>(100);

                while(reader.Read()) {
                    result.Add((short)reader["Revision"]);
                }

                CloseReader(reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// The the names of the pages with attachments.
        /// </summary>
        /// <returns>The names of the pages with attachments.</returns>
        public string[] GetPagesWithAttachments()
        {
            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Attachment", new string[] { "Page" });
            query = queryBuilder.GroupBy(query, new[] { "Page" });
            query = queryBuilder.OrderBy(query, new[] { "Page" }, new[] { Ordering.Asc });

            DbCommand command = builder.GetCommand(connString, query, new List<Parameter>());

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<string> result = new List<string>(100);

                while(reader.Read()) {
                    result.Add(reader["Page"] as string);
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets the recent changes of the Wiki.
        /// </summary>
        /// <returns>The recent Changes, oldest to newest.</returns>
        public RecentChange[] GetRecentChanges()
        {
            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("RecentChange", new string[] { "Page", "Title", "MessageSubject", "DateTime", "User", "Change", "Description" });
            query = queryBuilder.OrderBy(query, new string[] { "DateTime" }, new Ordering[] { Ordering.Asc });

            DbCommand command = builder.GetCommand(connString, query, new List<Parameter>());

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<RecentChange> result = new List<RecentChange>(100);

                while(reader.Read()) {
                    result.Add(new RecentChange(reader["Page"] as string, reader["Title"] as string,
                        GetNullableColumn<string>(reader, "MessageSubject", ""),
                        (DateTime)reader["DateTime"], reader["User"] as string, RecentChangeFromChar(((string)reader["Change"])[0]),
                        GetNullableColumn<string>(reader, "Description", "")));
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Adds a new Message to a Page.
        /// </summary>
        /// <param name="page">The Page.</param>
        /// <param name="username">The Username.</param>
        /// <param name="subject">The Subject.</param>
        /// <param name="dateTime">The Date/Time.</param>
        /// <param name="body">The Body.</param>
        /// <param name="parent">The Parent Message ID, or -1.</param>
        /// <returns>True if the Message is added successfully.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="page"/>, <paramref name="username"/>, <paramref name="subject"/> or <paramref name="body"/> are <c>null</c>.</exception>
        /// <exception cref="ArgumentException">If <paramref name="username"/> or <paramref name="subject"/> are empty.</exception>
        /// <exception cref="ArgumentOutOfRangeException">If <paramref name="parent"/> is less than -1.</exception>
        public bool AddMessage(PageInfo page, string username, string subject, DateTime dateTime, string body, int parent)
        {
            if(page == null) throw new ArgumentNullException("page");
            if(username == null) throw new ArgumentNullException("username");
            if(username.Length == 0) throw new ArgumentException("Username cannot be empty", "username");
            if(subject == null) throw new ArgumentNullException("subject");
            if(subject.Length == 0) throw new ArgumentException("Subject cannot be empty", "subject");
            if(body == null) throw new ArgumentNullException("body"); // body can be empty
            if(parent < -1) throw new ArgumentOutOfRangeException("parent", "Invalid Parent Message ID");

            string nspace, name;
            NameTools.ExpandFullName(page.FullName, out nspace, out name);
            if(nspace == null) nspace = "";

            ICommandBuilder builder = GetCommandBuilder();
            DbConnection connection = builder.GetConnection(connString);
            DbTransaction transaction = BeginTransaction(connection);

            if(parent != -1 && FindMessage(GetMessages(transaction, page), parent) == null) {
                RollbackTransaction(transaction);
                return false;
            }

            QueryBuilder queryBuilder = new QueryBuilder(builder);

            short freeId = -1;

            string query = queryBuilder.SelectFrom("Message", new string[] { "Id" });
            query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
            query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.OrderBy(query, new string[] { "Id" }, new Ordering[] { Ordering.Desc });

            List<Parameter> parameters = new List<Parameter>(2);
            parameters.Add(new Parameter(ParameterType.String, "Page", name));
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));

            DbCommand command = builder.GetCommand(transaction, query, parameters);

            freeId = ExecuteScalar<short>(command, -1, false);

            if(freeId == -1) freeId = 0;
            else freeId++;

            query = queryBuilder.InsertInto("Message", new string[] { "Page", "Namespace", "Id", "Parent", "Username", "Subject", "DateTime", "Body" },
                new string[] { "Page", "Namespace", "Id", "Parent", "Username", "Subject", "DateTime", "Body" });

            parameters = new List<Parameter>(8);
            parameters.Add(new Parameter(ParameterType.String, "Page", name));
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
            parameters.Add(new Parameter(ParameterType.Int16, "Id", freeId));
            if(parent != -1) parameters.Add(new Parameter(ParameterType.Int16, "Parent", parent));
            else parameters.Add(new Parameter(ParameterType.Int16, "Parent", DBNull.Value));
            parameters.Add(new Parameter(ParameterType.String, "Username", username));
            parameters.Add(new Parameter(ParameterType.String, "Subject", subject));
            parameters.Add(new Parameter(ParameterType.DateTime, "DateTime", dateTime));
            parameters.Add(new Parameter(ParameterType.String, "Body", body));

            command = builder.GetCommand(transaction, query, parameters);

            int rows = ExecuteNonQuery(command, false);

            if(rows == 1) {
                IndexMessage(page, freeId, subject, dateTime, body, transaction);

                CommitTransaction(transaction);
                return true;
            }
            else {
                RollbackTransaction(transaction);
                return false;
            }
        }

        /// <summary>
        /// Gets the outgoing links of a page.
        /// </summary>
        /// <param name="page">The full name of the page.</param>
        /// <returns>The outgoing links.</returns>
        /// <exception cref="ArgumentNullException">If <b>page</b> is <c>null</c>.</exception>
        /// <exception cref="ArgumentException">If <b>page</b> is empty.</exception>
        public string[] GetOutgoingLinks(string page)
        {
            if(page == null) throw new ArgumentNullException("page");
            if(page.Length == 0) throw new ArgumentException("Page cannot be empty", "page");

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("OutgoingLink", new string[] { "Destination" });
            query = queryBuilder.Where(query, "Source", WhereOperator.Equals, "Source");
            query = queryBuilder.OrderBy(query, new[] { "Destination" }, new[] { Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Source", page));

            DbCommand command = builder.GetCommand(connString, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<string> result = new List<string>(20);

                while(reader.Read()) {
                    result.Add(reader["Destination"] as string);
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets all the Log Entries, sorted by date/time (oldest to newest).
        /// </summary>
        /// <returns>The Log Entries.</returns>
        public LogEntry[] GetLogEntries()
        {
            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Log", new string[] { "DateTime", "EntryType", "User", "Message" });
            query = queryBuilder.OrderBy(query, new string[] { "DateTime" }, new Ordering[] { Ordering.Asc });

            DbCommand command = builder.GetCommand(connString, query, new List<Parameter>());

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<LogEntry> result = new List<LogEntry>(100);

                while(reader.Read()) {
                    result.Add(new LogEntry(EntryTypeFromChar((reader["EntryType"] as string)[0]),
                        (DateTime)reader["DateTime"], reader["Message"] as string, reader["User"] as string));
                }

                CloseReader(command, reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Cuts the recent changes if necessary.
        /// </summary>
        private void CutRecentChangesIfNecessary()
        {
            ICommandBuilder builder = GetCommandBuilder();
            DbConnection connection = builder.GetConnection(connString);
            DbTransaction transaction = BeginTransaction(connection);

            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectCountFrom("RecentChange");

            DbCommand command = builder.GetCommand(transaction, query, new List<Parameter>());

            int rows = ExecuteScalar<int>(command, -1, false);

            int maxChanges = int.Parse(host.GetSettingValue(SettingName.MaxRecentChanges));

            if(rows > maxChanges) {
                // Remove 10% of old changes to avoid 1-by-1 deletion every time a change is made
                int entriesToDelete = maxChanges / 10;
                if(entriesToDelete > rows) entriesToDelete = rows;
                //entriesToDelete += entriesToDelete / 10;

                // This code is not optimized, but it surely works in most DBMS
                query = queryBuilder.SelectFrom("RecentChange", new string[] { "Id" });
                query = queryBuilder.OrderBy(query, new string[] { "Id" }, new Ordering[] { Ordering.Asc });

                command = builder.GetCommand(transaction, query, new List<Parameter>());

                DbDataReader reader = ExecuteReader(command);

                List<int> ids = new List<int>(entriesToDelete);

                if(reader != null) {
                    while(reader.Read() && ids.Count < entriesToDelete) {
                        ids.Add((int)reader["Id"]);
                    }

                    CloseReader(reader);
                }

                if(ids.Count > 0) {
                    // Given that the IDs to delete can be many, the query is split in many chunks, each one deleting 50 items
                    // This works-around the problem of too many parameters in a RPC call of SQL Server
                    // See also CutLog

                    for(int chunk = 0; chunk <= ids.Count / MaxParametersInQuery; chunk++) {
                        query = queryBuilder.DeleteFrom("RecentChange");
                        List<string> parms = new List<string>(MaxParametersInQuery);
                        List<Parameter> parameters = new List<Parameter>(MaxParametersInQuery);

                        for(int i = chunk * MaxParametersInQuery; i < Math.Min(ids.Count, (chunk + 1) * MaxParametersInQuery); i++) {
                            parms.Add("P" + i.ToString());
                            parameters.Add(new Parameter(ParameterType.Int32, parms[parms.Count - 1], ids[i]));
                        }

                        query = queryBuilder.WhereIn(query, "Id", parms.ToArray());

                        command = builder.GetCommand(transaction, query, parameters);

                        if(ExecuteNonQuery(command, false) < 0) {
                            RollbackTransaction(transaction);
                            return;
                        }
                    }
                }
            }

            CommitTransaction(transaction);
        }

        /// <summary>
        /// Lists the Directories in the specified directory.
        /// </summary>
        /// <param name="transaction">A database transaction.</param>
        /// <param name="directory">The full directory name, for example "/my/directory". Null, empty or "/" for the root directory.</param>
        /// <returns>The list of Directories in the Directory.</returns>
        private string[] ListDirectories(DbTransaction transaction, string directory)
        {
            directory = PrepareDirectory(directory);

            ICommandBuilder builder = GetCommandBuilder();

            if(!DirectoryExists(transaction, directory)) {
                RollbackTransaction(transaction);
                throw new ArgumentException("Directory does not exist", "directory");
            }

            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Directory", new string[] { "FullPath" });
            query = queryBuilder.Where(query, "Parent", WhereOperator.Equals, "Parent");

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Parent", directory));
            query = queryBuilder.OrderBy(query, new[] { "FullPath" }, new[] { Ordering.Asc });

            DbCommand command = builder.GetCommand(transaction, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<string> result = new List<string>(20);

                while(reader.Read()) {
                    result.Add(reader["FullPath"] as string);
                }

                CloseReader(reader);

                return result.ToArray();
            }
            else return null;
        }

        /// <summary>
        /// Gets all the Categories in a namespace.
        /// </summary>
        /// <param name="connection">A database connection.</param>
        /// <param name="nspace">The namespace.</param>
        /// <returns>All the Categories in the namespace. The array is not sorted.</returns>
        private CategoryInfo[] GetCategories(DbConnection connection, NamespaceInfo nspace)
        {
            string nspaceName = nspace != null ? nspace.Name : "";

            ICommandBuilder builder = GetCommandBuilder();
            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Category", "CategoryBinding", new string[] { "Name", "Namespace" }, new string[] { "Category", "Namespace" }, Join.LeftJoin,
                new string[] { "Name", "Namespace" }, new string[] { "Page" });
            query = queryBuilder.Where(query, "Category", "Namespace", WhereOperator.Equals, "Namespace");
            query = queryBuilder.OrderBy(query, new string[] { "Category_Name", "CategoryBinding_Page" }, new Ordering[] { Ordering.Asc, Ordering.Asc });

            List<Parameter> parameters = new List<Parameter>(1);
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspaceName));

            DbCommand command = builder.GetCommand(connection, query, parameters);

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                List<CategoryInfo> result = new List<CategoryInfo>(20);
                List<string> pages = new List<string>(50);

                string prevName = "|||";
                string name = null;

                while(reader.Read()) {
                    name = reader["Category_Name"] as string;

                    if(name != prevName) {
                        if(prevName != "|||") {
                            result[result.Count - 1].Pages = pages.ToArray();
                            pages.Clear();
                        }

                        result.Add(new CategoryInfo(NameTools.GetFullName(reader["Category_Namespace"] as string, name), this));
                    }

                    prevName = name;
                    if(!IsDBNull(reader, "CategoryBinding_Page")) {
                        pages.Add(NameTools.GetFullName(reader["Category_Namespace"] as string, reader["CategoryBinding_Page"] as string));
                    }
                }

                CloseReader(reader);

                if(result.Count > 0) result[result.Count - 1].Pages = pages.ToArray();

                return result.ToArray();
            }
            else return null;
        }