C# 數據保存到Excel

C#將數據保存到Excel時，數據需要保持原來的類型，而不是簡單的分為數字和文本將數據保存。

public static bool SaveByOLEDB(DataTable dt, string path)
		{
			bool success = true;

			string connStr = "Provider=Microsoft.Jet.OleDb.4.0;" + "data source=" + path + ";Extended Properties=Excel 8.0;";//僅支持2003格式的Excel
			OleDbConnection conn = new OleDbConnection(connStr);
			OleDbCommand cmd = new OleDbCommand();
			cmd.Connection = conn;
			cmd.CommandType = CommandType.Text;
			try
			{
				conn.Open();
				string cmdText = "Create Table sheet1 (";

				for(int i = 0; i < dt.Columns.Count; i++)
				{
					string columnName = dt.Columns[i].ColumnName;
					cmdText += " "+ columnName;
					string typeName =GetExcelMapDataType(dt.Columns[i].DataType.Name);
					cmdText += " "+ typeName;
					if(i == dt.Columns.Count - 1)
					{
						cmdText += ")";
					}
					else
					{
						cmdText += ",";
					}
				}

				cmd.CommandText = cmdText;
				cmd.ExecuteNonQuery();

				for (int i = 0; i < dt.Rows.Count; i++)
				{
					cmdText = "Insert into sheet1 values (";
					for (int j = 0; j < dt.Columns.Count; j++)
					{
						string columnName = dt.Columns[j].ColumnName;
						cmdText += "@" + columnName;
						cmd.Parameters.AddWithValue("@" + columnName, dt.Rows[i][columnName]);
						if (j == dt.Columns.Count - 1)
						{
							cmdText += ")";
						}
						else
						{
							cmdText += ",";
						}
					}
					cmd = new OleDbCommand(cmdText, conn);
					for (int j = 0; j < dt.Columns.Count; j++)
					{
						string columnName = dt.Columns[j].ColumnName;
						string columnType = dt.Columns[j].DataType.Name;
						if(columnType.ToLower() == "datetime")
						{
							OleDbParameter pm = new OleDbParameter();
							pm.ParameterName = "@" + columnName;
							pm.OleDbType = OleDbType.Date;
							pm.Value = dt.Rows[i][columnName];
							cmd.Parameters.Add(pm);

							continue;
						}
						cmdText += "@" + columnName;
						cmd.Parameters.AddWithValue("@" + columnName, dt.Rows[i][columnName]);
					}

					cmd.ExecuteNonQuery();
				}

				

			}
			catch(Exception ex)
			{

			}
			finally
			{
				conn.Close();
				conn.Dispose();
			}
			return success;
		}

　　一些特殊類型需要轉為OLEDB兼容的數據類型。

static string GetExcelMapDataType(string dataType)
		{
			string result = dataType;
			switch (dataType.ToLower())
			{
				case "int":
				case "int32":
					result = "INTEGER";
					break;
				case "datetime":
					result = "DATE";
					break;
				case "boolean":
					result = "bit";
					break;
				default:
					break;
			}

			return result;
		}

　　附Excel的數據類型

在進行轉換時OLEDB作為中間層實現了C#數據類型和Excel數據類型的映射，但是C#數據類型轉為OLEDB數據類型這兒需要自己處理。

圖片截取自：https://www.promotic.eu/en/pmdoc/Subsystems/Db/Excel/DataTypes.htm