asp.net 数据访问层基类

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

namespace sosuo8.DBUtility
{

public abstract class DbHelperSQL
{
//数据库连接字符串

public static string connectionString = ConfigurationManager.ConnectionStrings["Conn"].ToString();


public static SqlConnection conn = new SqlConnection(connectionString);
public DbHelperSQL()
{
}

#region 公用方法
/// <summary>
/// 判断是否存在某表的某个字段
/// </summary>
/// <param>表名称</param>
/// <param>列名称</param>
/// <returns>是否存在</returns>
public static bool ColumnExists(string tableName, string columnName)
{
string sql = "select count(1) from syscolumns where [id]=object_id('" + tableName + "') and [name]='" + columnName + "'";
object res = GetSingle(sql);
if (res == null)
{
return false;
}
return Convert.ToInt32(res) > 0;
}
public static int GetMaxID(string FieldName, string TableName,string wherestr)
{
string strsql = "select max(" + FieldName + ")+1 from " + TableName;
if (wherestr != string.Empty)
{
strsql += " where " + wherestr;
}
object obj = DbHelperSQL.GetSingle(strsql);
if (obj == null)
{
return 1;
}
else
{
return int.Parse(obj.ToString());
}
}
public static bool Exists(string strSql)
{
object obj = DbHelperSQL.GetSingle(strSql);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}
/// <summary>
/// 表是否存在
/// </summary>
/// <param></param>
/// <returns></returns>
public static bool TabExists(string TableName)
{
string strsql = "select count(*) from sysobjects where id = object_id(N'[" + TableName + "]') and OBJECTPROPERTY(id, N'IsUserTable') = 1";
//string strsql = "SELECT count(*) FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[" + TableName + "]') AND type in (N'U')";
object obj = DbHelperSQL.GetSingle(strsql);
int cmdresult;
if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
{
cmdresult = 0;
}
else
{
cmdresult = int.Parse(obj.ToString());
}
if (cmdresult == 0)
{
return false;
}
else
{
return true;
}
}
}