【数据库】SQL通用方法集结号

public static class DBHelper
    {
        private static SqlConnection connection;  //定义连接

        public static SqlConnection Connection    //打开连接
        {
            get
            {
                string connectionString = ConfigurationManager.ConnectionStrings["sqlcon"].ConnectionString;
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                }
                else if (connection.State == ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }

        //不带参数的执行命令
        public static int ExecuteCommand(string sql)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            return cmd.ExecuteNonQuery();
            connection.Close();
        }
        //带参数的执行命令
        public static int ExecuteCommand(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql,Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
            connection.Close();
        }

     //不带参数，执行受影响行数

        public static int GetScalar(string sql)
        {
            SqlCommand cmd = new SqlCommand(sql,Connection);
            return Convert.ToInt32(cmd.ExecuteScalar());
            connection.Close();
        }

     //带参数，执行受影响的行数

        public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return Convert.ToInt32(cmd.ExecuteScalar());
            connection.Close();
        }

    //不带参数，向前式读取数据库

        public static SqlDataReader GetReader(string sql)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
            connection.Close();
        }

     //带参数，向前式读取数据库

        public static SqlDataReader GetReader(string sql,params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
            connection.Close();
        }

        public static DataTable GetDataSet(string sql)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql,Connection);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

        public static DataTable GetDataSet(string sql,params SqlParameter[] values)
        {
            DataSet ds = new DataSet();
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            return ds.Tables[0];
        }

    }
}