三种数据库链接connection方法.

1,access数据库
写一个简单的例子: 使用access数据库sales.mdb并将查询出的结果用datagrid显示
OleDbConnection thisConnection = new OleDbConnection(
    "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Server.MapPath("Sales.mdb"));
   thisConnection.Open();
   
   OleDbCommand thisCommand = thisConnection.CreateCommand();
   thisCommand.CommandText = "select * from Customers";

   this.DataGridAcc.DataSource = thisCommand.ExecuteReader();
   this.DataGridAcc.DataBind();

   thisConnection.Close();

OleDbConnection格式为 Provider=Microsoft.Jet.OLEDB.4.0;Data Source= ***.mdb
可用相对路径 Server.MapPath("Sales.mdb")); 也可加上绝对路径 .. / , data\access\sales.mdb .

2,Excel数据库
其它部分代码与连接access类似,区别在于connection 和 select .
OleDbConnection thisConnection = new OleDbConnection(
    "Provider=Microsoft.Jet.OLEDB.4.0;Extended Properties=Excel 8.0;Data Source=" + Server.MapPath("Products.xls"));
多加了一句
Extended Properties=Excel 8.0;

查询语句中表名的写法要注意
"select * from [Products$]";
在Excel表中查询名为 Products 时,前后加上 [ $] .

3,Sql数据库
类似
SqlConnection thisConnection = new SqlConnection(
    "Server = (local); DataBase = NorthWind;integrated security = SSPI");