C# QueryBuilder.UpdateIncrement方法代码示例

        /// <summary>
        /// Retrieves a Page Attachment.
        /// </summary>
        /// <param name="pageInfo">The Page Info that owns the Attachment.</param>
        /// <param name="name">The name of the Attachment, for example "myfile.jpg".</param>
        /// <param name="destinationStream">A Stream object used as <b>destination</b> of a byte stream,
        /// i.e. the method writes to the Stream the file content.</param>
        /// <param name="countHit">A value indicating whether or not to count this retrieval in the statistics.</param>
        /// <returns><c>true</c> if the Attachment is retrieved, <c>false</c> otherwise.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="pageInfo"/>, <paramref name="name"/> or <paramref name="destinationStream"/> are <c>null</c>.</exception>
        /// <exception cref="ArgumentException">If <paramref name="name"/> is empty or if <paramref name="destinationStream"/> does not support writing,
        /// or if the page does not have attachments or if the attachment does not exist.</exception>
        public bool RetrievePageAttachment(PageInfo pageInfo, string name, System.IO.Stream destinationStream, bool countHit)
        {
            if(pageInfo == null) throw new ArgumentNullException("pageInfo");
            if(name == null) throw new ArgumentNullException("name");
            if(name.Length == 0) throw new ArgumentException("Name cannot be empty", "name");
            if(destinationStream == null) throw new ArgumentNullException("destinationStream");
            if(!destinationStream.CanWrite) throw new ArgumentException("Cannot write into Destination Stream", "destinationStream");

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

            if(!AttachmentExists(transaction, pageInfo, name)) {
                RollbackTransaction(transaction);
                throw new ArgumentException("Attachment does not exist", "name");
            }

            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.SelectFrom("Attachment", new string[] { "Size", "Data" });
            query = queryBuilder.Where(query, "Name", WhereOperator.Equals, "Name");
            query = queryBuilder.AndWhere(query, "Page", WhereOperator.Equals, "Page");

            List<Parameter> parameters = new List<Parameter>(2);
            parameters.Add(new Parameter(ParameterType.String, "Name", name));
            parameters.Add(new Parameter(ParameterType.String, "Page", pageInfo.FullName));

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

            DbDataReader reader = ExecuteReader(command);

            if(reader != null) {
                bool done = false;

                if(reader.Read()) {
                    int read = ReadBinaryColumn(reader, "Data", destinationStream);
                    done = (long)read == (long)reader["Size"];
                }

                CloseReader(reader);

                if(!done) {
                    RollbackTransaction(transaction);
                    return false;
                }
            }
            else {
                RollbackTransaction(transaction);
                return false;
            }

            if(countHit) {
                // Update download count
                query = queryBuilder.UpdateIncrement("Attachment", "Downloads", 1);
                query = queryBuilder.Where(query, "Name", WhereOperator.Equals, "Name");
                query = queryBuilder.AndWhere(query, "Page", WhereOperator.Equals, "Page");

                parameters = new List<Parameter>(2);
                parameters.Add(new Parameter(ParameterType.String, "Name", name));
                parameters.Add(new Parameter(ParameterType.String, "Page", pageInfo.FullName));

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

                int rows = ExecuteNonQuery(command, false);
                if(rows != 1) {
                    RollbackTransaction(transaction);
                    return false;
                }
            }

            CommitTransaction(transaction);

            return true;
        }

        /// <summary>
        /// Deletes the Backups of a Page, up to a specified revision.
        /// </summary>
        /// <param name="page">The Page to delete the backups of.</param>
        /// <param name="revision">The newest revision to delete (newer revision are kept) o -1 to delete all the Backups.</param>
        /// <returns><c>true</c> if the deletion succeeded, <c>false</c> otherwise.</returns>
        /// <exception cref="ArgumentNullException">If <paramref name="page"/> is <c>null</c>.</exception>
        /// <exception cref="ArgumentOutOfRangeException">If <paramref name="revision"/> is less than -1.</exception>
        public bool DeleteBackups(PageInfo page, int revision)
        {
            if(page == null) throw new ArgumentNullException("page");
            if(revision < -1) throw new ArgumentOutOfRangeException("revision", "Invalid Revision");

            // 1. Retrieve target content (revision-1 = first kept revision)
            // 2. Replace the current content (delete, store)
            // 3. Delete all older revisions up to the specified on (included) "N-m...N"
            // 4. Re-number remaining revisions starting from FirstRevision (zero) to revision-1 (don't re-number revs -1, -100)

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

            if(GetPage(transaction, page.FullName) == null) {
                RollbackTransaction(transaction);
                return false;
            }

            int[] baks = GetBackups(transaction, page);
            if(baks.Length > 0 && revision > baks[baks.Length - 1]) {
                RollbackTransaction(transaction);
                return true;
            }

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

            QueryBuilder queryBuilder = new QueryBuilder(builder);

            string query = queryBuilder.DeleteFrom("PageContent");
            query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
            query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
            if(revision != -1) query = queryBuilder.AndWhere(query, "Revision", WhereOperator.LessThanOrEqualTo, "Revision");
            query = queryBuilder.AndWhere(query, "Revision", WhereOperator.GreaterThanOrEqualTo, "FirstRevision");

            List<Parameter> parameters = new List<Parameter>(4);
            parameters.Add(new Parameter(ParameterType.String, "Page", name));
            parameters.Add(new Parameter(ParameterType.String, "Namespace", nspace));
            if(revision != -1) parameters.Add(new Parameter(ParameterType.Int16, "Revision", revision));
            parameters.Add(new Parameter(ParameterType.Int16, "FirstRevision", FirstRevision));

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

            int rows = ExecuteNonQuery(command, false);

            if(rows == -1) {
                RollbackTransaction(transaction);
                return false;
            }

            if(revision != -1) {
                int revisionDelta = revision + 1;

                query = queryBuilder.UpdateIncrement("PageContent", "Revision", -revisionDelta);
                query = queryBuilder.Where(query, "Page", WhereOperator.Equals, "Page");
                query = queryBuilder.AndWhere(query, "Namespace", WhereOperator.Equals, "Namespace");
                query = queryBuilder.AndWhere(query, "Revision", WhereOperator.GreaterThanOrEqualTo, "FirstRevision");

                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, "FirstRevision", FirstRevision));

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

                rows = ExecuteNonQuery(command, false);

                if(rows > 0) CommitTransaction(transaction);
                else RollbackTransaction(transaction);

                return rows >= 0;
            }
            else {
                CommitTransaction(transaction);
                return true;
            }
        }