IBatis 批量插入数据之SqlBulkCopy

public void AddLetters(IList<int> customerIds, string title, string content, LetterEnum.LetterType type)
        {
            // 插入内容，获取内容ID
            var msgContentId = this.AddLetterContent(title, content, 2);

            // 站内信接收者表字段初始化
            var letterDataTable = this.InitDataTable();
            foreach (var customerId in customerIds)
            {
                var letterDataRow = letterDataTable.NewRow();
            
                letterDataRow["CustomerId"] = customerId;

                letterDataRow["MsgContentId"] = msgContentId;

                letterDataTable.Rows.Add(letterDataRow);
            }

            using (var conn = new SqlConnection(_sqlMapper.DataSource.ConnectionString))
            {
                conn.Open();

                using (var sqlBulkCopy = new SqlBulkCopy(conn))
                {
                    sqlBulkCopy.DestinationTableName = "Letter";
                    sqlBulkCopy.BatchSize = letterDataTable.Rows.Count;

                    if (letterDataTable.Rows.Count > 0)
                    {
                        sqlBulkCopy.WriteToServer(letterDataTable);
                    }
                }
            }
        }

        /// <summary>
        /// 初始化Letter表结构
        /// </summary>
        private DataTable InitDataTable()
        {
            var dataTable = new DataTable();

            using (var conn = new SqlConnection(_sqlMapper.DataSource.ConnectionString))
            {
                var queryString = string.Format(@"select top 0 * from {0}", "Letter");
                var adapter = new SqlDataAdapter(queryString, conn);
                adapter.Fill(dataTable);
              
            }

            return dataTable;
        }