C# 链接sql数据库通用类库

using System;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

namespace Farm.DB
{
    /// <summary>
    /// 数据库访问类 DB
    /// 无需实例化，静态访问
    /// </summary>
    public static class SqlHelper
    {
        //获取数据库连接字符串，其属于静态变量且只读，项目中所有文档可以直接使用，但不能修改
        private static string connectionString = System.Configuration.ConfigurationManager.ConnectionStrings["SqlConnectionStrings"].ConnectionString;
        private static SqlConnection conn = new SqlConnection();
        private static int throwError = -1; //-1:提示错误 0:屏蔽错误 1:扔出错误

        static SqlHelper()
        {
            throwError = 1;
        }

        /// <summary>
        /// 错误处理
        /// -1:提示错误
        /// 0:屏蔽错误
        /// 1:抛出错误
        /// </summary>
        public static int ThrowError
        {
            get { return throwError; }
            set { throwError = value; }
        }

        /// <summary>
        /// 打开数据库
        /// </summary>
        /// <param name="connectionString">连接字符串</param>
        public static void Open(string connectionString)
        {
            if (conn.State != ConnectionState.Open)
            {
                try
                {
                    conn.ConnectionString = connectionString;
                    conn.Open();
                }
                catch (SqlException exp)
                {
                    if (throwError == -1)
                    {
                        System.Web.HttpContext.Current.Response.Write("错误，错误信息如下：/n" + exp.Message);
                        System.Web.HttpContext.Current.Response.End();
                    }
                    else if (throwError == 1)
                    {
                        throw exp;
                    }
                }
            }
        }

        /// <summary>
        /// 打开数据库
        /// </summary>
        public static void Open()
        {
            Open(connectionString);
        }

        /// <summary>
        /// 关闭数据库
        /// </summary>
        public static void Close()
        {
            try
            {
                if (conn.State == ConnectionState.Open)
                {
                    conn.Close();
                    conn.Dispose();
                }
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("错误，错误信息如下：/n" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
            }
        }
        /// <summary>
        /// 获取数DataTable数据表
        /// </summary>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="cmdParms">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回DataTable数据表</returns>
        public static DataTable ExecuteDataTable(string cmdText, params SqlParameter[] cmdParms)
        {
            DataTable dt = new DataTable();
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = CommandType.Text;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
            }
            return dt;
        }
        public static DataTable ExecuteDataTable(string cmdText,CommandType cmdType, params SqlParameter[] cmdParms)
        {
            DataTable dt = new DataTable();
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = cmdType;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
            }
            return dt;
        }
        /// <summary>
        /// 调用视图
        /// </summary>
        /// <param name="cmdText">查询视图语句</param>
        /// <returns></returns>
        public static DataTable ExecuteDataTable(string cmdText)
        {
            DataTable dt = new DataTable();
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = CommandType.Text;
                SqlDataAdapter da = new SqlDataAdapter(cmd);
                da.Fill(dt);
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
            }
            return dt;
        }
        /// <summary>
        /// 通过sql语句获取SqlDataReader对象
        /// </summary>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="cmdParms">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>SqlDataReader对象</returns>
        public static SqlDataReader ExecuteReader(string cmdText, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = CommandType.Text;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                SqlDataReader dr = cmd.ExecuteReader();
                return dr;
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return null;
            }
        }
        //add by hry
        public static SqlDataReader ExecuteReader(string cmdText,CommandType cmdType, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = cmdType;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                SqlDataReader dr = cmd.ExecuteReader();
                return dr;
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return null;
            }
        }
 

        /// <summary>
        /// 通过sql语句返回第一行第一列
        /// </summary>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="cmdParms">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回的列</returns>
        public static object ExecuteScalar(string cmdText, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = CommandType.Text;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                return cmd.ExecuteScalar();
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return 0;
            }
        }
        //add By hanglyang
        public static object ExecuteScalar(string cmdText,CommandType cmdType, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = cmdType;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                return cmd.ExecuteScalar();
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return 0;
            }
        }

        /// <summary>
        /// 通过sql语句执行增、删、改命令
        /// </summary>
        /// <param name="cmdText">存储过程的名字或者 T-SQL 语句</param>
        /// <param name="cmdParms">以数组形式提供SqlCommand命令中用到的参数列表</param>
        /// <returns>返回影响的行数</returns>
        public static int ExecuteNonQuery(string cmdText, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = CommandType.StoredProcedure;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                int ret = cmd.ExecuteNonQuery();
                return ret;
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return 0;
            }
        }
        //add lyang
        public static int ExecuteNonQuery(string cmdText, CommandType cmdType, params SqlParameter[] cmdParms)
        {
            try
            {
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                cmd.CommandText = cmdText;
                cmd.CommandType = cmdType;
                if (cmdParms != null)
                {
                    foreach (SqlParameter parm in cmdParms)
                        cmd.Parameters.Add(parm);
                }
                int ret = cmd.ExecuteNonQuery();
                return ret;
            }
            catch (SqlException exp)
            {
                if (throwError == -1)
                {
                    System.Web.HttpContext.Current.Response.Write("发生错误：" + exp.Message);
                    System.Web.HttpContext.Current.Response.End();
                }
                else if (throwError == 1)
                {
                    throw exp;
                }
                return 0;
            }
        }

    }

}