数据库连接的多种方式(一)

public class Helper

    {

        private static string cons = "server=.;uid=sa;pwd=;database=pubs";

        //查询

        public static DataTable ExecuteDataQuery(string sql)

        {

            using (SqlConnection con = new SqlConnection(cons))

            {

                con.Open();

                DataTable tbl = new DataTable();

                SqlDataAdapter adap = new SqlDataAdapter(sql, con);

                adap.Fill(tbl);

                return tbl;

            }


        }

        public static SqlDataReader ExecuteDataQuery(string sql)

        {

            SqlConnection con = new SqlConnection(cons);

            SqlCommand cmd = new SqlCommand(sql, con);

            con.Open();

            return cmd.ExecuteReader(CommandBehavior.CloseConnection);


        }

        //增删改

        public static void ExecuteNonQuery(string sql)

        {

            using (SqlConnection con = new SqlConnection(cons))

            {

                con.Open();

                SqlCommand cmd = new SqlCommand(sql, con);

                cmd.ExecuteNonQuery();

            }

        }

    }

------------------------------------------------------------------------------------------------------------------------------

using System;
using System.Collections;
using System.Collections.Specialized;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;


/// <summary>
/// Copyright (C) 2004-2008 LiTianPing 
/// 数据访问基础类(基于SQLServer)
/// 用户可以修改满足自己项目的需要。
/// </summary>
public abstract class DbHelperSQL
{
    protected static string connectionString = CFunc.ConnectionString;
    public static SqlConnection conn = null;

    public static void connColse()
    {
        if (conn.State == ConnectionState.Open)
        {
            conn.Close();
        }
    }
    #region 执行简单SQL语句

    /// <summary>
    /// 执行SQL语句，返回影响的记录数
    /// </summary>
    /// <param name="SQLString">SQL语句</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSql(string SQLString)
    {
        conn = new SqlConnection(connectionString);

        using (SqlCommand cmd = new SqlCommand(SQLString, conn))
        {
            try
            {
                conn.Open();
                int rows = cmd.ExecuteNonQuery();
                return rows;
            }
            catch (System.Data.SqlClient.SqlException E)
            {
                throw new Exception(E.Message);
            }
            finally
            {
                cmd.Dispose();
                conn.Close();
            }
        }

    }

    /// <summary>
    /// 执行多条SQL语句，实现数据库事务。
    /// </summary>
    /// <param name="SQLStringList">多条SQL语句</param>  
    public static void ExecuteSqlTran(ArrayList SQLStringList)
    {
        conn = new SqlConnection(connectionString);

        conn.Open();
        SqlCommand cmd = new SqlCommand();
        cmd.Connection = conn;
        SqlTransaction tx = conn.BeginTransaction();
        cmd.Transaction = tx;
        try
        {
            for (int n = 0; n < SQLStringList.Count; n++)
            {
                string strsql = SQLStringList[n].ToString();
                if (strsql.Trim().Length > 1)
                {
                    cmd.CommandText = strsql;
                    cmd.ExecuteNonQuery();
                }
            }
            tx.Commit();
        }
        catch (System.Data.SqlClient.SqlException E)
        {
            tx.Rollback();
            throw new Exception(E.Message);
        }
        finally
        {
            cmd.Dispose();
            conn.Close();
        }

    }
    /// <summary>
    /// 执行带一个存储过程参数的的SQL语句。
    /// </summary>
    /// <param name="SQLString">SQL语句</param>
    /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特

殊符号，可以通过这个方式添加</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSql(string SQLString, string content)
    {
        conn = new SqlConnection(connectionString);
        SqlCommand cmd = new SqlCommand(SQLString, conn);
        System.Data.SqlClient.SqlParameter myParameter = new

System.Data.SqlClient.SqlParameter("@content", SqlDbType.NText);
        myParameter.Value = content;
        cmd.Parameters.Add(myParameter);
        try
        {
            conn.Open();
            int rows = cmd.ExecuteNonQuery();
            return rows;
        }
        catch (System.Data.SqlClient.SqlException E)
        {
            throw new Exception(E.Message);
        }
        finally
        {
            cmd.Dispose();
            conn.Close();
        }
    }
    /// <summary>
    /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)
    /// </summary>
    /// <param name="strSQL">SQL语句</param>
    /// <param name="fs">图像字节,数据库的字段类型为image的情况</param>
    /// <returns>影响的记录数</returns>
    public static int ExecuteSqlInsertImg(string strSQL, byte[] fs)
    {
        conn = new SqlConnection(connectionString);
        SqlCommand cmd = new SqlCommand(strSQL, conn);
        System.Data.SqlClient.SqlParameter myParameter = new

System.Data.SqlClient.SqlParameter("@fs", SqlDbType.Image);
        myParameter.Value = fs;
        cmd.Parameters.Add(myParameter);
        try
        {
            conn.Open();
            int rows = cmd.ExecuteNonQuery();
            return rows;
        }
        catch (System.Data.SqlClient.SqlException E)
        {
            throw new Exception(E.Message);
        }
        finally
        {
            cmd.Dispose();
            conn.Close();
        }
    }

    /// <summary>
    /// 执行一条计算查询结果语句，返回查询结果（object）。
    /// </summary>
    /// <param name="SQLString">计算查询结果语句</param>
    /// <returns>查询结果（object）</returns>
    public static object GetSingle(string SQLString)
    {
        conn = new SqlConnection(connectionString);

        using (SqlCommand cmd = new SqlCommand(SQLString, conn))
        {
            try
            {
                conn.Open();
                object obj = cmd.ExecuteScalar();
                if ((Object.Equals(obj, null)) || (Object.Equals(obj,

System.DBNull.Value)))
                {
                    return null;
                }
                else
                {
                    return obj;
                }
            }
            catch (System.Data.SqlClient.SqlException e)
            {
                conn.Close();
                throw new Exception(e.Message);
            }
            finally
            {
                cmd.Dispose();
                conn.Close();
            }
        }
    }
    /// <summary>
    /// 执行查询语句，返回SqlDataReader
    /// </summary>
    /// <param name="strSQL">查询语句</param>
    /// <returns>SqlDataReader</returns>
    public static SqlDataReader ExecuteReader(string strSQL)
    {//使用完后请关闭conn
        conn = new SqlConnection(connectionString);
        SqlCommand cmd = new SqlCommand(strSQL, conn);
        try
        {
            conn.Open();
            SqlDataReader myReader = cmd.ExecuteReader();
            return myReader;
        }
        catch (System.Data.SqlClient.SqlException e)
        {
            throw new Exception(e.Message);
        }
    }