c#中只连接数据库一次

Question

这就是所谓的多层架构里的数据链接层DLL了.
在某一个类里把连接数据库的方法封装,当然还有其他一些数据库操作的类都可以封起来.用的时候只要调用就可以.

Answer 1

    public static class DbConnect
    {
        private const string m_strConnString = "Provider=microsoft.jet.oledb.4.0;data source=c:\\school.mdb";         public static OleDbConnection GetConnection()
        {
            return new OleDbConnection(m_strConnString); 
        }
    }        protected void Page_Load(object sender, EventArgs e)
        {
            OleDbConnection conn = DbConnect.GetConnection();
            conn.Open();
        }如果只是达到楼主要求的功能的话，这样就可以了，但是这么做会把数据库的操作都放到表现层，未体现出分层的概念。

Answer 2

你看看PETSHOP先你的软件不是一个好的面向对象的软件。不要把数据层和表现层放在一起。

Answer 3

namespace PetShop.DBUtility {    /// <summary>
    /// The SqlHelper class is intended to encapsulate high performance, 
    /// scalable best practices for common uses of SqlClient.
    /// </summary>
    public abstract class SqlHelper {        //Database connection strings
        public static readonly string ConnectionStringLocalTransaction = ConfigurationManager.ConnectionStrings["SQLConnString1"].ConnectionString;
        public static readonly string ConnectionStringInventoryDistributedTransaction = ConfigurationManager.ConnectionStrings["SQLConnString2"].ConnectionString;
        public static readonly string ConnectionStringOrderDistributedTransaction = ConfigurationManager.ConnectionStrings["SQLConnString3"].ConnectionString;
public static readonly string ConnectionStringProfile = ConfigurationManager.ConnectionStrings["SQLProfileConnString"].ConnectionString;

        // Hashtable to store cached parameters
        private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) against the database specified in the connection string 
        /// using the provided parameters.
        /// </summary>
        /// <res>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </res>
        /// <param name="connectionString">a valid connection string for a SqlConnection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {            SqlCommand cmd = new SqlCommand();            using (SqlConnection conn = new SqlConnection(connectionString)) {
                PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
                int val = cmd.ExecuteNonQuery();
                cmd.Parameters.Clear();
                return val;
            }
        }        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) against an existing database connection 
        /// using the provided parameters.
        /// </summary>
        /// <res>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </res>
        /// <param name="conn">an existing database connection</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {            SqlCommand cmd = new SqlCommand();            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }        /// <summary>
        /// Execute a SqlCommand (that returns no resultset) using an existing SQL Transaction 
        /// using the provided parameters.
        /// </summary>
        /// <res>
        /// e.g.:  
        ///  int result = ExecuteNonQuery(connString, CommandType.StoredProcedure, "PublishOrders", new SqlParameter("@prodid", 24));
        /// </res>
        /// <param name="trans">an existing sql transaction</param>
        /// <param name="commandType">the CommandType (stored procedure, text, etc.)</param>
        /// <param name="commandText">the stored procedure name or T-SQL command</param>
        /// <param name="commandParameters">an array of SqlParamters used to execute the command</param>
        /// <returns>an int representing the number of rows affected by the command</returns>
        public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters) {
            SqlCommand cmd = new SqlCommand();
            PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }
看看高手的对你有帮助他用WEB.CONFIG的读取

Answer 4

－　－
看看我的资源里有用Access做的东西。里面有源码。

Answer 5

楼上的都已经回答了，自己写一个类，把数据库相关的操作封装好。以后需要的时候，直接调用就行了。class DB
    {
        private bool DBIsAlive;        public SqlConnection Conn1;
        public SqlCommand Cmd1;
        public SqlDataReader sdr;
        public string ErrMsg;
        public string DBLocation, DBName, DBUser, DBPaswd;
        private string con_str;
        private int ConnectDB()
        {
            int reuslt = 1;//·µ»ØÖµ
            if (DBLocation == "" || DBName == "" || DBUser == "" || DBPaswd == "")
                return -1;  
            string ConStr = "uid=" + DBUser + ";password=" + DBPaswd + ";database=" + DBName + ";server=" + DBLocation;
            Conn1 = new SqlConnection();
            Conn1.ConnectionString = ConStr;
            con_str = ConStr;
            
            try
            {
                Conn1.Open();
                DBIsAlive = true;
            }
            catch(Exception ee)
            {
                Conn1.Close();
                DBIsAlive = false;
                ErrMsg = ee.Message;
                reuslt = -2;    //Êý¾Ý¿âÁ¬½Óʧ°Ü
            }
            return reuslt;
        }        private int DisconnectDB()
        {
            int result = 1;
            if (DBIsAlive)
            {
                try
                {
                    Conn1.Close();
                    //Conn1.Dispose();
                }
                catch(Exception ee)
                {
                    ErrMsg = ee.Message;
                    result = -3; //Êý¾Ý¿â¶Ï¿ªÊ§°Ü
                }
            }
            else
            {
                try
                {
                    //Conn1.Dispose();
                    Conn1.Close();
                }
                catch(Exception ee)
                {
                    result = -3;
                    ErrMsg = ee.Message;
                }
            }
            return result;
        }        public bool DB_Content_Test()
        {
            bool result = false;
            if (ConnectDB() == 1)
                result = true;
            if (DisconnectDB() != 1)
                result = false;
            return result;
        }                public SqlDataReader SelectDetial(string command)
        {
            
            if (command != null)
            {
                ConnectDB();
                Cmd1 = new SqlCommand();
                Cmd1.CommandText = command;
                Cmd1.Connection = Conn1;
                sdr = Cmd1.ExecuteReader();
            }
            return sdr;
        
        }        public void UpdateDetial(string command)
        {            if (command != null)
            {
                ConnectDB();
                Cmd1 = new SqlCommand();
                Cmd1.CommandText = command;
                Cmd1.Connection = Conn1;
                Cmd1.ExecuteNonQuery();
            }
                    }
        
    }