C# update join,delete join

public static int UpdateJoin(DbFactory factory, string relationKey, string foreignKey, Dictionary<string, object> data, string condition, Joins mode, out string sql)
        {
            int count = data.Count;
            if (count == 0)
            {
                throw new ArgumentException("data");
            }
            string table = relationKey.Substring(0, relationKey.IndexOf(SqlBuilder.JoinSymbol)), foreignTable = foreignKey.Substring(0, foreignKey.IndexOf(SqlBuilder.JoinSymbol));
            count *= 8 + Math.Max(table.Length, foreignTable.Length);
            StringBuilder sb = new StringBuilder(count);
            using (Dictionary<string, object>.Enumerator e = data.GetEnumerator())
            {
                e.MoveNext();
                sb.Append(e.Current.Key).Append("=").AppendValue(e.Current.Value);
                while (e.MoveNext())
                {
                    sb.Append(SqlBuilder.Separator).Append(e.Current.Key).Append("=").AppendValue(e.Current.Value);
                }
            }
            switch (factory.ProviderName)
            {
                case DbProvider.Sql:
                    sql = String.Concat("UPDATE [", table, "] SET ", sb.ToString(), " FROM [", table, "] ", mode.ToString(), " JOIN [", foreignTable, "] ON ", relationKey, "=", foreignKey, SqlBuilder.Space, condition);
                    break;
                case DbProvider.OleDb:
                    sql = String.Concat("UPDATE [", table, "] ", mode.ToString(), " JOIN [", foreignTable, "] ON ", relationKey, "=", foreignKey, " SET ", sb.ToString(), SqlBuilder.Space, condition);
                    break;
                default:
                    throw new NotSupportedException();
            }
            return DbBase.ExecuteNonQuery(factory, sql);
        }

        public static int DeleteJoin(DbFactory factory, string relationKey, string foreignKey, string condition, Joins mode, out string sql)
        {
            string table = relationKey.Substring(0, relationKey.IndexOf(SqlBuilder.JoinSymbol)), foreignTable = foreignKey.Substring(0, foreignKey.IndexOf(SqlBuilder.JoinSymbol));
            switch (factory.ProviderName)
            {
                case DbProvider.Sql:
                    sql = String.Concat("DELETE FROM [", table, "] FROM [", table, "] ", mode.ToString(), " JOIN [", foreignTable, "] ON ", relationKey, "=", foreignKey, SqlBuilder.Space, condition);
                    break;
                case DbProvider.OleDb:
                    sql = String.Concat("DELETE ", table, ".*,", foreignTable, ".* FROM [", table, "] ", mode.ToString(), " JOIN [", foreignTable, "] ON ", relationKey, "=", foreignKey, SqlBuilder.Space, condition);
                    break;
                default:
                    throw new NotSupportedException();
            }
            return DbBase.ExecuteNonQuery(factory, sql);
        }