sqlhelp使用的问题，报错：SqlHelper 类型初始值设定项引发异常

Question

本帖最后由 xiaozhanger 于 2010-04-26 12:56:25 编辑

Answer 1

断点，看一下ConnectionStringVote的内容

Answer 2

ConfigurationManager.ConnectionStrings["DB"].ConnectionString;
在webconfig中有没有名为DB的连接串？

Answer 3

public abstract class SqlHelper你为什么要声明为abstract????

Answer 4

web.config中的连接字符串有问题!仔细看看!

Answer 5

检查ConfigurationManager.ConnectionStrings["DB"].ConnectionString;
单步跟踪

Answer 6

看web.config 里面节点为connectionString 中设置的<add name="DB" connectionString="中链接字符串是否正确

Answer 7

给你个标准的SQLhelperusing System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;
/*********************************
 * 类名：DBHelper
 * 功能描述：提供数据访问基础操作
 * ******************************/
namespace NetView.DAL
{
    public static class DBHelper
    {
        //数据库连接属性
        private static SqlConnection connection;
        public static SqlConnection Connection
        {
            get
            {
                string connectionString = ConfigurationManager.ConnectionStrings["NetViewConnectionString"].ConnectionString;
                if (connection == null)
                {
                    connection = new SqlConnection(connectionString);
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Closed)
                {
                    connection.Open();
                }
                else if (connection.State == System.Data.ConnectionState.Broken)
                {
                    connection.Close();
                    connection.Open();
                }
                return connection;
            }
        }
        /// <summary>
        /// 执行无参SQL语句
        /// </summary>
        public static int ExecuteCommand(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = cmd.ExecuteNonQuery();
            return result;
        }
        /// <summary>
        /// 执行有参SQL语句
        /// </summary>
        public static int ExecuteCommand(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            return cmd.ExecuteNonQuery();
        }
        /// <summary>
        /// 执行无参SQL语句，并返回执行行数
        /// </summary>
        public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }
        /// <summary>
        /// 执行有参SQL语句，并返回执行行数
        /// </summary>
        public static int GetScalar(string sql, params SqlParameter[] values)
        {
            SqlCommand cmd = new SqlCommand(sql, Connection);
            cmd.Parameters.AddRange(values);
            int result = Convert.ToInt32(cmd.ExecuteScalar());
            return result;
        }
        /// <summary>
        /// 执行无参SQL语句，并返SqlDataReader
        /// </summary>
        public static SqlDataReader GetReader(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            SqlDataReader reader = cmd.ExecuteReader();
            return reader;
        }
        /// <summary>
        /// 执行有参SQL语句，并返SqlDataReader
        /// </summary>
        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;
        }   
    }
}Web.Config<connectionStrings>
<add name="NetViewConnectionString" connectionString="Data Source=.;Initial Catalog=NetView;User ID=sa;password=123456" providerName="System.Data.SqlClient"/>
</connectionStrings>