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Question

using System;
using System.Data;
using System.Data.SqlClient;
using System.Collections.Generic;
using System.Windows.Forms;namespace Test
{
    static class ProDatabase
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new frmlogin());
           
        }
        ///   <summary>   
        ///   打开数据库连接   
        ///   </summary>   
        ///   <returns>数据库连接</returns>   
        public static SqlConnection OpenConnection()
        {
            SqlConnection Conn = new SqlConnection();
            Conn.ConnectionString = "Persist Security Info=False;User ID=sa;Initial Catalog=Test;Data Source=."";
            Conn.Open();            return Conn;
        }       }
}
我是想写Winform程序//我在一个类中定义数据库连接///在winform 的页面中怎样来访问了???

Answer 1

在同一项目中直接新建一个类文件，在里面写了，在WINFORM的程序直接可以引用

Answer 2

如果这个类是Static的就直接引在Form中用他的方法: ProDatabase.SqlConnection ().如果这个类不是Static的,就在Form中产生一个它的实例再引用实例的方法.

Answer 3

private System.Data.SqlClient.SqlConnection _connection;
        private System.Data.SqlClient.SqlCommand _command;
        private System.Data.SqlClient.SqlDataAdapter _adapter;
        private System.Data.DataSet _dataSet;            _dataSet = new System.Data.DataSet();
            try
            {
                this.Connection.Open();
                this.Command.CommandText = System.Configuration.ConfigurationManager.AppSettings["CommandText"];
                this.Command.CommandType = CommandType.Text;
                this.Adapter.Fill(_dataSet);
                System.Data.DataTable testTable = _dataSet.Tables[0];
            }
            catch { }
            finally
            {
                this.Connection.Close();
            }        public System.Data.SqlClient.SqlConnection Connection
        {
            get
            {
                if (_connection == null)
                {
                    _connection = new System.Data.SqlClient.SqlConnection();
                    _connection.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;
                }                return _connection;
            }
            set
            {
                _connection = value;
                Command.Connection = value;
            }
        }        public System.Data.SqlClient.SqlCommand Command
        {
            get
            {
                if (_command == null)
                {
                    _command = new System.Data.SqlClient.SqlCommand();
                }                return _command;
            }
        }        public System.Data.SqlClient.SqlDataAdapter Adapter
        {
            get
            {
                if (_adapter == null)
                {
                    _adapter = new System.Data.SqlClient.SqlDataAdapter(Command.CommandText, Connection);
                }                return _adapter;
            }
        }app.config<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
      <add name="connectionString" connectionString="Data Source=localhost; Initial Catalog=pubs; User ID=sa;Password=;"/>
    </connectionStrings>
  <appSettings>
    <add key="CommandText" value="select * from authors"/>
  </appSettings>
</configuration>