通过OleDB连接方式,访问Access,Excel数据库.

OleDbConnectionStringBuilder oleConStr = new OleDbConnectionStringBuilder();

Access 连接信息
oleConStr.ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + myDBFileName +
                                  ";User Id=admin;Password=;";

Excel 连接信息
string myExcelConStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + myDBFileName + ";Extended Properties=Excel 8.0;";
       
        myExcelConStr =
                @"Provider=Microsoft.Jet.OLEDB.4.0;" +
                @"Data Source=" + myDBFileName + ";" +
                @"Extended Properties=" + Convert.ToChar(34).ToString() +
                @"Excel 8.0;" + ExcelConnectionOptions() + Convert.ToChar(34).ToString();

        public bool Headers
        {
            get { return HasHeaders; }
            set { HasHeaders = value; }
        }

        public bool MixedData
        {
            get { return IsMixedData; }
            set { IsMixedData = value; }
        }

        private string ExcelConnectionOptions()
        {
            string strOpts = "";
            if (this.MixedData == true)
                strOpts += "Imex=2;";
            if (this.Headers == true)
                strOpts += "HDR=Yes;";
            else
                strOpts += "HDR=No;";
            return strOpts;
        }

=======查询数据===========
 OleDbConnection OleConn = new OleDbConnection(oleConStr.ConnectionString);
       OleDbCommand cmd;
       string SqlStr = "  Select top 1 *  from [" + newMaTolName + "] ";
       cmd = new OleDbCommand(SqlStr, OleConn);
       OleDbDataAdapter OleDapt = new OleDbDataAdapter();
       OleDapt.SelectCommand = cmd;
       OleConn.Open();
       DataSet myDS = new DataSet();
       OleDapt.Fill(myDS);
注意:如果是Excel数据库需在表名后加"$";

=======增加字段===========
SqlStr = "  ALTER TABLE  [" + newMaTolName.Replace("$","") + "]   ADD IsRead decimal,RowNo long IDENTITY(1,1)  ";
cmd = new OleDbCommand(SqlStr, OleConn);
int affectRows = cmd.ExecuteNonQuery();

=======在DataSet表中增加一列=======
myDS 是已保存有数据的DataSet
if (myDS.Tables[0].Rows.Count < 1)
                {
                    return IsSuccess;
                }

                DataTable dt = myDS.Tables[0];

                DataColumn dc = new DataColumn();
                dc.DataType = Type.GetType("System.String");

                dc.DefaultValue = 1;
                dc.ColumnName = "MaTolName";
                dt.Columns.Add(dc);
                //给该列赋值   
                for (int i = 0; i < dt.Rows.Count; i++)
                {
                    dt.Rows[i]["MaTolName"] = myMaTolName;
                }
                dt.DataSet.AcceptChanges();

=======获取数据源的框架信息,如其中的表名等.==============
System.Data.DataTable dt= OleConn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

=======获取与更新 DataGrid中的数据改变,并更新数据源.==========================
DataTable dtChanges = dt.GetChanges();
OleDbCommand oleCmd;
OleDbDataAdapter oleda = new OleDbDataAdapter(oleCmd);     
oleda.InsertCommand = new OleDbCommand(strInsert,oleConn);
oleda.UpdateCommand = new OleDbCommand(strUpdate,oleConn); 
oleAdapter.Update(dtChanges); 

        private void CreateNewTable()
        {
           
            System.Data.DataTable table = new DataTable("Student");
  
            DataColumn column;
            DataRow row;

         
            column = new DataColumn();
            column.DataType = System.Type.GetType("System.Int32");
            column.ColumnName = "SID";
            column.AutoIncrement = true;
            column.ReadOnly = false;
            column.Unique = true;       
            table.Columns.Add(column);

          
            column = new DataColumn();
            column.DataType = System.Type.GetType("System.String");
            column.ColumnName = "Name";
            column.AutoIncrement = false;
            column.Caption = "Name";
            column.ReadOnly = false;
            column.DefaultValue = "myName";
            column.Unique = false;
            table.Columns.Add(column);

            //设置表的主键
            DataColumn[] PrimaryKeyColumns = new DataColumn[1];
            PrimaryKeyColumns[0] = table.Columns["SID"];
            table.PrimaryKey = PrimaryKeyColumns;
            table.AcceptChanges();

           
            DataSet  dataSet = new DataSet();
            dataSet.Tables.Add(table);

        
            for (int i = 0; i <= 2; i++)
            {
                row = table.NewRow();
                //row["SID"] = i;
                //row["Name"] = "name " + i;
                table.Rows.Add(row);
            }
            dataSet.AcceptChanges();
            this.dataGrid1.DataSource = dataSet.Tables[0];
        }

=======表的复制=========
//创建新表dataTableDest
DataTable dataTableDest = new DataTable(); 
//将表dataTableSource的结构复制到新表dataTableDest中
dataTableDest = dataTableSource.Clone(); 
//然后再复制数据到新表中
foreach(DataRow dr in dataTableSource.Rows) 
{ 
//使用ImportRow()方法复制数据。若用dataTableDest.Rows.Add(dr)将会出错：System.ArgumentException: 该行已经属于另一个表。            
dataTableDest.ImportRow(dr); 
}
直接用下面的方法就行了
dataTableDest = dataTableSource.Copy();

========创建表=================
        DataTable dt = new DataTable("TableName");
//增加列
        dt.Columns.Add("column0", System.Type.GetType("System.String"));
        dt.Columns.Add(new DataColumn("IsChild", typeof(bool)));
        DataColumn dc = new DataColumn("column1", System.Type.GetType("System.Boolean"));
        dt.Columns.Add(dc);
//增加行
        DataRow dr = dt.NewRow();
        dr["column0"] = "Good";
        dr["column1"] = true;
        dt.Rows.Add(dr);
        //Doesn't initialize the row
        DataRow dr1 = dt.NewRow();
        dt.Rows.Add(dr1);
//选择行
        //Search the second row 如果没有赋值,则用is null来select
        DataRow[] drs = dt.Select("column1 is null");
        DataRow[] drss = dt.Select("column0 = 'Good'");
//复制表包括数据
        DataTable dtNew = dt.Copy();
//只复制表的架构
        DataTable dtOnlyScheme = dt.Clone();
//增加行并赋值
        //Method 1
        DataRow droperate = dt.Rows[0];
        droperate["column0"] = "AXzhz";
        droperate["column1"] = false;
        //Method 2
        droperate[0] = "AXzhz";
        droperate[1] = false;
        //Method 3
        dt.Rows[0]["column0"] = "AXzhz";
        dt.Rows[0]["column1"] = false;
        //Method 4
        dt.Rows[0][0] = "AXzhz";
        dt.Rows[0][1] = false;
        dtOnlyScheme.Rows.Add(dt.Rows[0].ItemArray);

//获取行的状态
        if (dt.Rows[0].RowState == DataRowState.Unchanged)
        {
          
        }

//将表转换成xml数据流形式
        System.IO.TextWriter tw = new System.IO.StringWriter();
            //if TableName is empty, WriteXml() will throw Exception.
            dtNeedCoveret.TableName=dtNeedCoveret.TableName.Length==0?"Table_AX":dtNeedCoveret.TableName;
            dtNeedCoveret.WriteXml(tw);
            dtNeedCoveret.WriteXmlSchema(tw);


        System.IO.TextReader trDataTable = new System.IO.StringReader(xml.Substring(0, xml.IndexOf("<?xml")));
            System.IO.TextReader trSchema = new System.IO.StringReader(xml.Substring(xml.IndexOf("<?xml")));
            DataTable dtReturn = new DataTable();
            dtReturn.ReadXmlSchema(trSchema);
            dtReturn.ReadXml(trDataTable);


//对表中的数据进行筛选
        //It's so strange that the second row has been filtered
        //the second row show in GridView never
        //It means null field will be filter always.
        //Filter the all conditions
        dt.DefaultView.RowFilter = "column1 <> true";
        //dt.DefaultView.RowFilter = "column1 = true";

        dt.DefaultView.RowStateFilter = DataViewRowState.Added;

//对表的数据排序
        //Stupid method
        DataRow[] drsss = dt.Select(String.Empty, "column0 DESC , column1 ASC");
        //Clever method
        dt.DefaultView.Sort = "column0 , column1 ASC";     
        dt.DefaultView.Sort = "ID ,Name ASC";
        dt=dt.DefaultView.ToTable();


//表的合并

        //两个结构相同的DT合并
        /**//// <summary>
        /// 将两个列不同的DataTable合并成一个新的DataTable
        /// </summary>
        /// <param name="dt1">表1</param>
        /// <param name="dt2">表2</param>
        /// <returns>合并过的新表</returns>
        private DataTable UnionSameDataTable(DataTable dt1, DataTable dt2)
        {
            DataTable dt3 = dt1.Clone();

            object[] obj = new object[dt3.Columns.Count];
            for (int i = 0; i < dt1.Rows.Count; i++)
            {
                dt1.Rows[i].ItemArray.CopyTo(obj, 0);
                dt3.Rows.Add(obj);
            }

            for (int i = 0; i < dt2.Rows.Count; i++)
            {
                dt2.Rows[i].ItemArray.CopyTo(obj, 0);
                dt3.Rows.Add(obj);
            }
            return dt3;
        }

        //两个结构不同的DT合并
        /**//// <summary>
        /// 将两个列不同的DataTable合并成一个新的DataTable
        /// </summary>
        /// <param name="dt1">表1</param>
        /// <param name="dt2">表2</param>
        /// <returns>合并过的新表</returns>
        private DataTable UniteDataTable(DataTable dt1, DataTable dt2)
        {
            DataTable dt3 = dt1.Clone();
            for (int i = 0; i < dt2.Columns.Count; i++)
            {
                dt3.Columns.Add(dt2.Columns[i].ColumnName);
            }
            object[] obj = new object[dt3.Columns.Count];

            for (int i = 0; i < dt1.Rows.Count; i++)
            {
                dt1.Rows[i].ItemArray.CopyTo(obj, 0);
                dt3.Rows.Add(obj);
            }

            if (dt1.Rows.Count >= dt2.Rows.Count)
            {
                for (int i = 0; i < dt2.Rows.Count; i++)
                {
                    for (int j = 0; j < dt2.Columns.Count; j++)
                    {
                        dt3.Rows[i][j + dt1.Columns.Count] = dt2.Rows[i][j].ToString();
                    }
                }
            }
            else
            {
                DataRow dr3;
                for (int i = 0; i < dt2.Rows.Count - dt1.Rows.Count; i++)
                {
                    dr3 = dt3.NewRow();
                    dt3.Rows.Add(dr3);
                }
                for (int i = 0; i < dt2.Rows.Count; i++)
                {
                    for (int j = 0; j < dt2.Columns.Count; j++)
                    {
                        dt3.Rows[i][j + dt1.Columns.Count] = dt2.Rows[i][j].ToString();
                    }
                }
            }
            return dt3;
        }


        //多个 结构相同的DataTable合并

        public DataTable GetAllEntrysDataTable()
        {
            DataTable newDataTable = GetEntrysDataTable(0).Clone();

            object[] obj = new object[newDataTable.Columns.Count];

            for (int i = 0; i < entryGroups.GetEntryGroupCount(); i++)
            {
                for (int j = 0; j < GetEntrysDataTable(i).Rows.Count; j++)
                {
                    GetEntrysDataTable(i).Rows[j].ItemArray.CopyTo(obj, 0);
                    newDataTable.Rows.Add(obj);
                }
            }
            return newDataTable;
        }

//执行DataTable中的查询返回新的DataTable
        //方法一
        /**//// <summary>
        /// 执行DataTable中的查询返回新的DataTable
        /// </summary>
        /// <param name="dt">源数据DataTable</param>
        /// <param name="condition">查询条件</param>
        /// <returns></returns>
        private DataTable GetNewDataTable(DataTable dt, string condition)
        {
            DataTable newdt = new DataTable();
            newdt = dt.Clone();
            DataRow[] dr = dt.Select(condition);
            for (int i = 0; i < dr.Length; i++)
            {
                newdt.ImportRow((DataRow)dr[i]);
            }
            return newdt;//返回的查询结果
        }

        //方法二
        /**//// <summary>
        /// 执行DataTable中的查询返回新的DataTable
        /// </summary>
        /// <param name="dt">源数据DataTable</param>
        /// <param name="condition">查询条件</param>
        /// <returns></returns>
        private DataTable GetNewDataTable(DataTable dt, string condition)
        {
            DataTable newdt = new DataTable();
            newdt = dt.Clone();
            DataRow[] rows = dt.Select(condition);
            foreach (DataRow row in rows)
            {
                newdt.Rows.Add(row.ItemArray);
            }
            return newdt;
        }