コード例 #1
0
        /// <summary>
        /// Execute a SELECT query.
        /// </summary>
        /// <param name="tableName">The table from which you wish to SELECT.</param>
        /// <param name="indexStart">The starting index for retrieval; used for pagination in conjunction with maxResults and orderByClause.  orderByClause example: ORDER BY created DESC.</param>
        /// <param name="maxResults">The maximum number of results to retrieve.</param>
        /// <param name="returnFields">The fields you wish to have returned.  Null returns all.</param>
        /// <param name="filter">The expression containing the SELECT filter (i.e. WHERE clause data).</param>
        /// <param name="orderByClause">Specify an ORDER BY clause if desired.</param>
        /// <returns>A DataTable containing the results.</returns>
        public DataTable Select(string tableName, int?indexStart, int?maxResults, List <string> returnFields, Expression filter, string orderByClause)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }

            string        query = "";
            DataTable     result;
            List <Column> tableDetails = DescribeTable(tableName);

            switch (DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.SelectQuery(tableName, indexStart, maxResults, returnFields, filter, orderByClause);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.SelectQuery(tableName, indexStart, maxResults, returnFields, filter, orderByClause);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.SelectQuery(tableName, indexStart, maxResults, returnFields, filter, orderByClause);
                break;
            }

            result = RawQuery(query);
            return(result);
        }
コード例 #2
0
        private string SanitizeString(string s)
        {
            if (String.IsNullOrEmpty(s))
            {
                return(String.Empty);
            }
            string ret = "";

            switch (DbType)
            {
            case DbTypes.MsSql:
                ret = MssqlHelper.SanitizeString(s);
                break;

            case DbTypes.MySql:
                ret = MysqlHelper.SanitizeString(s);
                break;

            case DbTypes.PgSql:
                ret = PgsqlHelper.SanitizeString(s);
                break;
            }

            return(ret);
        }
コード例 #3
0
        /// <summary>
        /// Drop the specified table.
        /// </summary>
        /// <param name="tableName">The table to drop.</param>
        public void DropTable(string tableName)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }

            string query = null;

            switch (_DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.DropTableQuery(tableName);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.DropTableQuery(tableName);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.DropTableQuery(tableName);
                break;
            }

            DataTable result = Query(query);
        }
コード例 #4
0
        /// <summary>
        /// Create a table with a specified name.
        /// </summary>
        /// <param name="tableName">The name of the table.</param>
        /// <param name="columns">Columns.</param>
        public void CreateTable(string tableName, List <Column> columns)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }
            if (columns == null || columns.Count < 1)
            {
                throw new ArgumentNullException(nameof(columns));
            }

            string query = null;

            switch (_DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.CreateTableQuery(tableName, columns);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.CreateTableQuery(tableName, columns);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.CreateTableQuery(tableName, columns);
                break;
            }

            DataTable result = Query(query);
        }
コード例 #5
0
        /// <summary>
        /// List all tables in the database.
        /// </summary>
        /// <returns>List of strings, each being a table name.</returns>
        public List <string> ListTables()
        {
            string        query      = null;
            DataTable     result     = null;
            List <string> tableNames = new List <string>();

            switch (_DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.LoadTableNamesQuery(_DatabaseName);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.LoadTableNamesQuery();
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.LoadTableNamesQuery();
                break;
            }

            result = Query(query);

            if (result != null && result.Rows.Count > 0)
            {
                switch (_DbType)
                {
                case DbTypes.MsSql:
                    foreach (DataRow curr in result.Rows)
                    {
                        tableNames.Add(curr["TABLE_NAME"].ToString());
                    }
                    break;

                case DbTypes.MySql:
                    foreach (DataRow curr in result.Rows)
                    {
                        tableNames.Add(curr["Tables_in_" + _DatabaseName].ToString());
                    }
                    break;

                case DbTypes.PgSql:
                    foreach (DataRow curr in result.Rows)
                    {
                        tableNames.Add(curr["tablename"].ToString());
                    }
                    break;
                }
            }

            return(tableNames);
        }
コード例 #6
0
        private string PreparedStringValue(string s)
        {
            switch (DbType)
            {
            case DbTypes.MsSql:
                return("'" + MssqlHelper.SanitizeString(s) + "'");

            case DbTypes.MySql:
                return("'" + MysqlHelper.SanitizeString(s) + "'");

            case DbTypes.PgSql:
                // uses $xx$ escaping
                return(PgsqlHelper.SanitizeString(s));
            }

            return(null);
        }
コード例 #7
0
        /// <summary>
        /// Execute a DELETE query.
        /// </summary>
        /// <param name="tableName">The table in which you wish to DELETE.</param>
        /// <param name="filter">The expression containing the DELETE filter (i.e. WHERE clause data).</param>
        /// <returns>A DataTable containing the results.</returns>
        public DataTable Delete(string tableName, Expression filter)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }
            if (filter == null)
            {
                throw new ArgumentNullException(nameof(filter));
            }

            #region Variables

            string        query = "";
            DataTable     result;
            List <Column> tableDetails     = DescribeTable(tableName);
            List <string> columnNames      = GetColumnNames(tableName);
            string        primaryKeyColumn = GetPrimaryKeyColumn(tableName);

            #endregion

            #region Build-DELETE-Query-and-Submit

            switch (DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.DeleteQuery(tableName, filter);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.DeleteQuery(tableName, filter);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.DeleteQuery(tableName, filter);
                break;
            }

            result = RawQuery(query);

            #endregion

            return(result);
        }
コード例 #8
0
        /// <summary>
        /// Execute a DELETE query.
        /// </summary>
        /// <param name="tableName">The table in which you wish to DELETE.</param>
        /// <param name="filter">The expression containing the DELETE filter (i.e. WHERE clause data).</param>
        /// <returns>A DataTable containing the results.</returns>
        public DataTable Delete(string tableName, Expression filter)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }
            if (filter == null)
            {
                throw new ArgumentNullException(nameof(filter));
            }

            #region Variables

            string    query = "";
            DataTable result;

            #endregion

            #region Build-DELETE-Query-and-Submit

            switch (_DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.DeleteQuery(tableName, filter);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.DeleteQuery(tableName, filter);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.DeleteQuery(tableName, filter);
                break;
            }

            result = Query(query);

            #endregion

            return(result);
        }
コード例 #9
0
        private void PopulateConnectionString()
        {
            ConnectionString = "";

            switch (DbType)
            {
            case DbTypes.MsSql:
                ConnectionString = MssqlHelper.ConnectionString(ServerIp, ServerPort, Username, Password, Instance, Database);
                break;

            case DbTypes.MySql:
                ConnectionString = MysqlHelper.ConnectionString(ServerIp, ServerPort, Username, Password, Database);
                break;

            case DbTypes.PgSql:
                ConnectionString = PgsqlHelper.ConnectionString(ServerIp, ServerPort, Username, Password, Database);
                break;
            }

            return;
        }
コード例 #10
0
        private void PopulateConnectionString()
        {
            ConnectionString = "";

            switch (_DbType)
            {
            case DbTypes.MsSql:
                ConnectionString = MssqlHelper.ConnectionString(_ServerIp, _ServerPort, _Username, _Password, _Instance, _DatabaseName);
                break;

            case DbTypes.MySql:
                ConnectionString = MysqlHelper.ConnectionString(_ServerIp, _ServerPort, _Username, _Password, _DatabaseName);
                break;

            case DbTypes.PgSql:
                ConnectionString = PgsqlHelper.ConnectionString(_ServerIp, _ServerPort, _Username, _Password, _DatabaseName);
                break;
            }

            return;
        }
コード例 #11
0
        /// <summary>
        /// Sanitize an input string.
        /// </summary>
        /// <param name="val">The value to sanitize.</param>
        /// <returns>A sanitized string.</returns>
        public string SanitizeString(string val)
        {
            if (String.IsNullOrEmpty(val))
            {
                return(val);
            }

            switch (_DbType)
            {
            case DbTypes.MsSql:
                return(MssqlHelper.SanitizeString(val));

            case DbTypes.MySql:
                return(MysqlHelper.SanitizeString(val));

            case DbTypes.PgSql:
                return(PgsqlHelper.SanitizeString(val));
            }

            throw new Exception("Unknown database type");
        }
コード例 #12
0
        private void LoadTableDetails()
        {
            lock (LoadingTablesLock)
            {
                string    query  = "";
                DataTable result = new DataTable();
                Dictionary <string, List <Column> > tableDetails = new Dictionary <string, List <Column> >();

                foreach (string currTable in TableNames)
                {
                    #region Gather-Schema

                    List <Column> columns = new List <Column>();

                    switch (DbType)
                    {
                    case DbTypes.MsSql:
                        query = MssqlHelper.LoadTableColumnsQuery(Database, currTable);
                        break;

                    case DbTypes.MySql:
                        query = MysqlHelper.LoadTableColumnsQuery(Database, currTable);
                        break;

                    case DbTypes.PgSql:
                        query = PgsqlHelper.LoadTableColumnsQuery(Database, currTable);
                        break;
                    }

                    #endregion

                    #region Process-Schema

                    result = RawQuery(query);
                    if (result != null && result.Rows.Count > 0)
                    {
                        foreach (DataRow currColumn in result.Rows)
                        {
                            #region Process-Each-Column

                            /*
                             * public bool IsPrimaryKey;
                             * public string Name;
                             * public string DataType;
                             * public int? MaxLength;
                             * public bool Nullable;
                             */
                            Column tempColumn = new Column();
                            int    maxLength  = 0;

                            switch (DbType)
                            {
                            case DbTypes.MsSql:
                                #region Mssql

                                tempColumn.Name = currColumn["COLUMN_NAME"].ToString();
                                if (currColumn["CONSTRAINT_NAME"].ToString().StartsWith("PK_"))
                                {
                                    tempColumn.IsPrimaryKey = true;
                                }
                                else
                                {
                                    tempColumn.IsPrimaryKey = false;
                                }
                                tempColumn.DataType = currColumn["DATA_TYPE"].ToString();
                                if (!Int32.TryParse(currColumn["CHARACTER_MAXIMUM_LENGTH"].ToString(), out maxLength))
                                {
                                    tempColumn.MaxLength = null;
                                }
                                else
                                {
                                    tempColumn.MaxLength = maxLength;
                                }
                                if (String.Compare(currColumn["IS_NULLABLE"].ToString(), "YES") == 0)
                                {
                                    tempColumn.Nullable = true;
                                }
                                else
                                {
                                    tempColumn.Nullable = false;
                                }
                                break;

                                #endregion

                            case DbTypes.MySql:
                                #region Mysql

                                tempColumn.Name = currColumn["COLUMN_NAME"].ToString();
                                if (String.Compare(currColumn["COLUMN_KEY"].ToString(), "PRI") == 0)
                                {
                                    tempColumn.IsPrimaryKey = true;
                                }
                                else
                                {
                                    tempColumn.IsPrimaryKey = false;
                                }
                                tempColumn.DataType = currColumn["DATA_TYPE"].ToString();
                                if (!Int32.TryParse(currColumn["CHARACTER_MAXIMUM_LENGTH"].ToString(), out maxLength))
                                {
                                    tempColumn.MaxLength = null;
                                }
                                else
                                {
                                    tempColumn.MaxLength = maxLength;
                                }
                                if (String.Compare(currColumn["IS_NULLABLE"].ToString(), "YES") == 0)
                                {
                                    tempColumn.Nullable = true;
                                }
                                else
                                {
                                    tempColumn.Nullable = false;
                                }
                                break;

                                #endregion

                            case DbTypes.PgSql:
                                #region Pgsql

                                tempColumn.Name = currColumn["column_name"].ToString();
                                if (String.Compare(currColumn["is_primary_key"].ToString(), "YES") == 0)
                                {
                                    tempColumn.IsPrimaryKey = true;
                                }
                                else
                                {
                                    tempColumn.IsPrimaryKey = false;
                                }
                                tempColumn.DataType = currColumn["DATA_TYPE"].ToString();
                                if (!Int32.TryParse(currColumn["max_len"].ToString(), out maxLength))
                                {
                                    tempColumn.MaxLength = null;
                                }
                                else
                                {
                                    tempColumn.MaxLength = maxLength;
                                }
                                if (String.Compare(currColumn["IS_NULLABLE"].ToString(), "YES") == 0)
                                {
                                    tempColumn.Nullable = true;
                                }
                                else
                                {
                                    tempColumn.Nullable = false;
                                }
                                break;

                                #endregion
                            }

                            columns.Add(tempColumn);

                            #endregion
                        }

                        tableDetails.Add(currTable, columns);
                    }

                    #endregion
                }

                #region Replace-Table-Details

                TableDetails = new ConcurrentDictionary <string, List <Column> >();
                foreach (KeyValuePair <string, List <Column> > curr in tableDetails)
                {
                    TableDetails.TryAdd(curr.Key, curr.Value);
                }

                #endregion

                return;
            }
        }
コード例 #13
0
        private void LoadTableNames()
        {
            lock (LoadingTablesLock)
            {
                string    query  = "";
                DataTable result = new DataTable();

                #region Build-Query

                switch (DbType)
                {
                case DbTypes.MsSql:
                    query = MssqlHelper.LoadTableNamesQuery(Database);
                    break;

                case DbTypes.MySql:
                    query = MysqlHelper.LoadTableNamesQuery();
                    break;

                case DbTypes.PgSql:
                    query = PgsqlHelper.LoadTableNamesQuery();
                    break;
                }

                #endregion

                #region Process-Results

                result = RawQuery(query);
                List <string> tableNames = new List <string>();

                if (result != null && result.Rows.Count > 0)
                {
                    switch (DbType)
                    {
                    case DbTypes.MsSql:
                        foreach (DataRow curr in result.Rows)
                        {
                            tableNames.Add(curr["TABLE_NAME"].ToString());
                        }
                        break;

                    case DbTypes.MySql:
                        foreach (DataRow curr in result.Rows)
                        {
                            tableNames.Add(curr["Tables_in_" + Database].ToString());
                        }
                        break;

                    case DbTypes.PgSql:
                        foreach (DataRow curr in result.Rows)
                        {
                            tableNames.Add(curr["tablename"].ToString());
                        }
                        break;
                    }
                }

                if (tableNames != null && tableNames.Count > 0)
                {
                    TableNames = new ConcurrentList <string>();
                    foreach (string curr in tableNames)
                    {
                        TableNames.Add(curr);
                    }
                }

                #endregion

                return;
            }
        }
コード例 #14
0
        /// <summary>
        /// Execute an UPDATE query.
        /// </summary>
        /// <param name="tableName">The table in which you wish to UPDATE.</param>
        /// <param name="keyValuePairs">The key-value pairs for the data you wish to UPDATE.</param>
        /// <param name="filter">The expression containing the UPDATE filter (i.e. WHERE clause data).</param>
        /// <returns>A DataTable containing the results.</returns>
        public DataTable Update(string tableName, Dictionary <string, object> keyValuePairs, Expression filter)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }
            if (keyValuePairs == null || keyValuePairs.Count < 1)
            {
                throw new ArgumentNullException(nameof(keyValuePairs));
            }

            #region Variables

            string        query          = "";
            string        keyValueClause = "";
            DataTable     result;
            List <Column> tableDetails     = DescribeTable(tableName);
            List <string> columnNames      = GetColumnNames(tableName);
            string        primaryKeyColumn = GetPrimaryKeyColumn(tableName);

            #endregion

            #region Build-Key-Value-Clause

            int added = 0;
            foreach (KeyValuePair <string, object> curr in keyValuePairs)
            {
                if (String.IsNullOrEmpty(curr.Key))
                {
                    continue;
                }
                if (!columnNames.Contains(curr.Key))
                {
                    throw new ArgumentException("Column " + curr.Key + " does not exist in table " + tableName);
                }

                if (added == 0)
                {
                    if (curr.Value != null)
                    {
                        if (curr.Value is DateTime || curr.Value is DateTime?)
                        {
                            keyValueClause += PreparedFieldname(curr.Key) + "='" + DbTimestamp(DbType, (DateTime)curr.Value) + "'";
                        }
                        else if (curr.Value is int || curr.Value is long || curr.Value is decimal)
                        {
                            keyValueClause += PreparedFieldname(curr.Key) + "=" + curr.Value.ToString();
                        }
                        else
                        {
                            if (Helper.IsExtendedCharacters(curr.Value.ToString()))
                            {
                                keyValueClause += PreparedFieldname(curr.Key) + "=" + PreparedUnicodeValue(curr.Value.ToString());
                            }
                            else
                            {
                                keyValueClause += PreparedFieldname(curr.Key) + "=" + PreparedStringValue(curr.Value.ToString());
                            }
                        }
                    }
                    else
                    {
                        keyValueClause += PreparedFieldname(curr.Key) + "= null";
                    }
                }
                else
                {
                    if (curr.Value != null)
                    {
                        if (curr.Value is DateTime || curr.Value is DateTime?)
                        {
                            keyValueClause += "," + PreparedFieldname(curr.Key) + "='" + DbTimestamp(DbType, (DateTime)curr.Value) + "'";
                        }
                        else if (curr.Value is int || curr.Value is long || curr.Value is decimal)
                        {
                            keyValueClause += "," + PreparedFieldname(curr.Key) + "=" + curr.Value.ToString();
                        }
                        else
                        {
                            if (Helper.IsExtendedCharacters(curr.Value.ToString()))
                            {
                                keyValueClause += "," + PreparedFieldname(curr.Key) + "=" + PreparedUnicodeValue(curr.Value.ToString());
                            }
                            else
                            {
                                keyValueClause += "," + PreparedFieldname(curr.Key) + "=" + PreparedStringValue(curr.Value.ToString());
                            }
                        }
                    }
                    else
                    {
                        keyValueClause += "," + PreparedFieldname(curr.Key) + "= null";
                    }
                }
                added++;
            }

            #endregion

            #region Build-UPDATE-Query-and-Submit

            switch (DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.UpdateQuery(tableName, keyValueClause, filter);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.UpdateQuery(tableName, keyValueClause, filter);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.UpdateQuery(tableName, keyValueClause, filter);
                break;
            }

            result = RawQuery(query);

            #endregion

            return(result);
        }
コード例 #15
0
        /// <summary>
        /// Execute an INSERT query.
        /// </summary>
        /// <param name="tableName">The table in which you wish to INSERT.</param>
        /// <param name="keyValuePairs">The key-value pairs for the row you wish to INSERT.</param>
        /// <returns>A DataTable containing the results.</returns>
        public DataTable Insert(string tableName, Dictionary <string, object> keyValuePairs)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }
            if (keyValuePairs == null || keyValuePairs.Count < 1)
            {
                throw new ArgumentNullException(nameof(keyValuePairs));
            }

            #region Variables

            string        keys           = "";
            string        values         = "";
            string        query          = "";
            int           insertedId     = 0;
            string        retrievalQuery = "";
            DataTable     result;
            List <Column> tableDetails     = DescribeTable(tableName);
            List <string> columnNames      = GetColumnNames(tableName);
            string        primaryKeyColumn = GetPrimaryKeyColumn(tableName);

            #endregion

            #region Build-Key-Value-Pairs

            int added = 0;
            foreach (KeyValuePair <string, object> curr in keyValuePairs)
            {
                if (String.IsNullOrEmpty(curr.Key))
                {
                    continue;
                }
                if (!columnNames.Contains(curr.Key))
                {
                    throw new ArgumentException("Column " + curr.Key + " does not exist in table " + tableName);
                }

                if (added == 0)
                {
                    #region First

                    keys += PreparedFieldname(curr.Key);
                    if (curr.Value != null)
                    {
                        if (curr.Value is DateTime || curr.Value is DateTime?)
                        {
                            values += "'" + DbTimestamp(DbType, (DateTime)curr.Value) + "'";
                        }
                        else if (curr.Value is int || curr.Value is long || curr.Value is decimal)
                        {
                            values += curr.Value.ToString();
                        }
                        else
                        {
                            if (Helper.IsExtendedCharacters(curr.Value.ToString()))
                            {
                                values += PreparedUnicodeValue(curr.Value.ToString());
                            }
                            else
                            {
                                values += PreparedStringValue(curr.Value.ToString());
                            }
                        }
                    }
                    else
                    {
                        values += "null";
                    }

                    #endregion
                }
                else
                {
                    #region Subsequent

                    keys += "," + PreparedFieldname(curr.Key);
                    if (curr.Value != null)
                    {
                        if (curr.Value is DateTime || curr.Value is DateTime?)
                        {
                            values += ",'" + DbTimestamp(DbType, (DateTime)curr.Value) + "'";
                        }
                        else if (curr.Value is int || curr.Value is long || curr.Value is decimal)
                        {
                            values += "," + curr.Value.ToString();
                        }
                        else
                        {
                            if (Helper.IsExtendedCharacters(curr.Value.ToString()))
                            {
                                values += "," + PreparedUnicodeValue(curr.Value.ToString());
                            }
                            else
                            {
                                values += "," + PreparedStringValue(curr.Value.ToString());
                            }
                        }
                    }
                    else
                    {
                        values += ",null";
                    }

                    #endregion
                }

                added++;
            }

            #endregion

            #region Build-INSERT-Query-and-Submit

            switch (DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.InsertQuery(tableName, keys, values);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.InsertQuery(tableName, keys, values);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.InsertQuery(tableName, keys, values);
                break;
            }

            result = RawQuery(query);

            #endregion

            #region Post-Retrieval

            switch (DbType)
            {
            case DbTypes.MsSql:
                #region MsSql

                //
                // built into the query
                //
                break;

                #endregion

            case DbTypes.MySql:
                #region MySql

                if (!Helper.DataTableIsNullOrEmpty(result))
                {
                    bool idFound = false;

                    foreach (DataRow curr in result.Rows)
                    {
                        if (Int32.TryParse(curr["id"].ToString(), out insertedId))
                        {
                            idFound = true;
                            break;
                        }
                    }

                    if (!idFound)
                    {
                        result = null;
                    }
                    else
                    {
                        retrievalQuery = "SELECT * FROM " + tableName + " WHERE " + primaryKeyColumn + "=" + insertedId;
                        result         = RawQuery(retrievalQuery);
                    }
                }
                break;

                #endregion

            case DbTypes.PgSql:
                #region PgSql

                //
                // built into the query
                //
                break;

                #endregion
            }

            #endregion

            return(result);
        }
コード例 #16
0
        /// <summary>
        /// Show the columns and column metadata from a specific table.
        /// </summary>
        /// <param name="tableName">The table to view.</param>
        /// <returns>A list of column objects.</returns>
        public List <Column> DescribeTable(string tableName)
        {
            if (String.IsNullOrEmpty(tableName))
            {
                throw new ArgumentNullException(nameof(tableName));
            }

            string        query   = null;
            DataTable     result  = null;
            List <Column> columns = new List <Column>();

            switch (_DbType)
            {
            case DbTypes.MsSql:
                query = MssqlHelper.LoadTableColumnsQuery(_DatabaseName, tableName);
                break;

            case DbTypes.MySql:
                query = MysqlHelper.LoadTableColumnsQuery(_DatabaseName, tableName);
                break;

            case DbTypes.PgSql:
                query = PgsqlHelper.LoadTableColumnsQuery(_DatabaseName, tableName);
                break;
            }

            result = Query(query);
            if (result != null && result.Rows.Count > 0)
            {
                foreach (DataRow currColumn in result.Rows)
                {
                    #region Process-Each-Column

                    /*
                     * public bool PrimaryKey;
                     * public string Name;
                     * public string DataType;
                     * public int? MaxLength;
                     * public bool Nullable;
                     */

                    Column tempColumn = new Column();

                    tempColumn.Name = currColumn["COLUMN_NAME"].ToString();

                    int maxLength = 0;
                    if (!Int32.TryParse(currColumn["CHARACTER_MAXIMUM_LENGTH"].ToString(), out maxLength))
                    {
                        tempColumn.MaxLength = null;
                    }
                    else
                    {
                        tempColumn.MaxLength = maxLength;
                    }

                    tempColumn.Type = DataTypeFromString(currColumn["DATA_TYPE"].ToString());

                    if (String.Compare(currColumn["IS_NULLABLE"].ToString(), "YES") == 0)
                    {
                        tempColumn.Nullable = true;
                    }
                    else
                    {
                        tempColumn.Nullable = false;
                    }

                    switch (_DbType)
                    {
                    case DbTypes.MsSql:
                        if (currColumn["CONSTRAINT_NAME"] != null &&
                            currColumn["CONSTRAINT_NAME"] != DBNull.Value &&
                            !String.IsNullOrEmpty(currColumn["CONSTRAINT_NAME"].ToString()))
                        {
                            if (currColumn["CONSTRAINT_NAME"].ToString().ToLower().StartsWith("pk"))
                            {
                                tempColumn.PrimaryKey = true;
                            }
                        }
                        break;

                    case DbTypes.MySql:
                        if (currColumn["COLUMN_KEY"] != null &&
                            currColumn["COLUMN_KEY"] != DBNull.Value &&
                            !String.IsNullOrEmpty(currColumn["COLUMN_KEY"].ToString()))
                        {
                            if (currColumn["COLUMN_KEY"].ToString().ToLower().Equals("pri"))
                            {
                                tempColumn.PrimaryKey = true;
                            }
                        }
                        break;

                    case DbTypes.PgSql:
                        if (currColumn["IS_PRIMARY_KEY"] != null &&
                            currColumn["IS_PRIMARY_KEY"] != DBNull.Value &&
                            !String.IsNullOrEmpty(currColumn["IS_PRIMARY_KEY"].ToString()))
                        {
                            if (currColumn["IS_PRIMARY_KEY"].ToString().ToLower().Equals("yes"))
                            {
                                tempColumn.PrimaryKey = true;
                            }
                        }
                        break;
                    }

                    if (!columns.Exists(c => c.Name.Equals(tempColumn.Name)))
                    {
                        columns.Add(tempColumn);
                    }

                    #endregion
                }
            }

            return(columns);
        }