连接并读取C＃.MDB项目 [英] connect and read .MDB item with C#

问题描述

是否可以连接到本地MDB文件，并选择信息的单个位出来的吗？
我有一个表，在它的信息的一个位一个.mbd文件。我想有该记录被输出成一个参考禁用的文本框。我相信我能拿到DB开放，并运行查询，但不知道什么，我需要从中读取数据。

感谢

  VAR myDataTable =新的DataTable（）;使用（VAR连接如=新的OleDbConnection（提供者= Microsoft.JET.OLEDB.4.0;
 +数据源= C：\\menus\\\\
ewmenus\\menu.mdb;密码= ****））
 {
 conection.Open（）; 
 VAR的查询=选择SITEID从n_user 
变种适配器=新OleDbDataAdapter的（查询，连接如）; 
 OleDbCommandBuilder oleDbCommandBuilder =新的OleDbCommandBuilder（适配器）; 
} 
  

解决方案

如果只是要读取单场在你的数据库表，你可以使用一个 OleDbDataReader 在结果返回所需的字段。

  VAR myDataTable =新的DataTable（），可以循环和;使用（VAR连接如=新的OleDbConnection（提供者= Microsoft.JET.OLEDB.4.0;
 +数据源= C：\\menus\\\\
ewmenus\\menu.mdb;密码= ****））
 {
 conection.Open（）; 
 VAR的查询=选择SITEID从n_user 
 VAR命令=新的OleDbCommand（查询，连接如）; 
 VAR读卡器= Command.ExecuteReader却（）; 
，而（reader.Read（））
 textBox1.Text =读卡器[0]的ToString（）; 
 
} 
  

如果你只有一个记录，只有一个字段，一个更好的解决方案是方法的ExecuteScalar

  conection.Open（）; 
 //返回才刚刚一个字段
 VAR查询组成=选择SITEID从n_user其中userid = 1的一个记录的查询; 
 VAR命令=新的OleDbCommand（查询，连接如）; 
 INT结果=（int）的command.ExecuteScalar（）; //假设SITEID是一个整数
  

也许我还要提到的ExecuteScalar返回空的如果查询没有找到的用户ID匹配，所以最好要小心这里的转换

 对象result = command.ExecuteScalar（）; 
如果（结果！= NULL）
 INT用户ID =（int）的结果; 
 ..... 
  

Is it possible to connect to a local MDB file and pick a single bit of info out of it ? I have a table in a .mbd file with a single bit of info in it. I would like to have that record be output into a disabled textbox for a reference. I believe I can get the DB open, and run the query but no idea what I need to read from it.

thanks

var myDataTable = new DataTable();
        using (var conection = new OleDbConnection("Provider=Microsoft.JET.OLEDB.4.0;" + "data source=C:\\menus\\newmenus\\menu.mdb;Password=****"))
        {
            conection.Open();
            var query = "Select siteid From n_user";
            var adapter = new OleDbDataAdapter(query, conection);
            OleDbCommandBuilder oleDbCommandBuilder = new OleDbCommandBuilder(adapter);
        }

解决方案

To simply read a single field on your database table you could use an OleDbDataReader that could loop over the result and return the field required..

var myDataTable = new DataTable();
using (var conection = new OleDbConnection("Provider=Microsoft.JET.OLEDB.4.0;" + "data source=C:\\menus\\newmenus\\menu.mdb;Password=****"))
{
     conection.Open();
     var query = "Select siteid From n_user";
     var command = new OleDbCommand(query, conection);
     var reader = command.ExecuteReader();
     while(reader.Read())
         textBox1.Text = reader[0].ToString();

 }

if you have just one record and just one field then a better solution is the method ExecuteScalar

     conection.Open();
     // A query that returns just one record composed of just one field
     var query = "Select siteid From n_user where userid=1";
     var command = new OleDbCommand(query, conection);
     int result = (int)command.ExecuteScalar();  // Supposing that siteid is an integer

Probably I should also mention that ExecuteScalar returns null if the query doesn't find a match for the userid, so it is better to be careful with the conversion here

     object result = command.ExecuteScalar();
     if( result != null)
        int userID  = (int)result;
        .....

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