SQLHelper帮助类_下（支持多数据库的封装）

在上篇关于SQLHelper类中，主要针对SQLServer数据库进行的。在使用别的数据库，就要修改部分代码！所以今天就写一个支持多数据库的封装！主要用到枚举，读取config文件！接口的简单用法。获取连接等...

一.config配置文件：

  <connectionStrings>
    <add name="constr" connectionString="server=127.0.0.1;user id=用户名;password=密码;database=数据库名"/>
  </connectionStrings>
  <appSettings>
    <add key="database" value ="MYSQL"/>
  </appSettings>

关于连接字符串在SQLHelper帮助类_ 上 进行介绍  http://www.cnblogs.com/fengxuehuanlin/p/5271944.html

二.SqlHelper:

        private static string connstr;
         /// <summary>
         /// 从配置文件中获取连接字符串名,使用什么数据库
         /// <appSettings>中key名：database，value值:数据库
         /// <connectionStrings>name：constr
         /// </summary>
         static SqlHelper()
         {
             connstr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString; //获取config文件中连接字符串
             string databaseType = ConfigurationManager.AppSettings["database"].ToUpper();
             DBdatabase.database = AdoHelper.EnumParse<DatabaseList>(databaseType);   //将字符串转换成枚举类型
         }

         /// <summary>
         /// 获取相应数据库的连接
         /// </summary>
         /// <returns></returns>
         public static IDbConnection getConnection()
         {
             string value = DBdatabase.database.ToString();
             DatabaseList database= AdoHelper.EnumParse<DatabaseList>(value);
             switch(database)
             {
                 case DatabaseList.MYSQL:
                     return new MySqlConnection(connstr);
                 case  DatabaseList.SQLSERVER:
                     return new SqlConnection(connstr);
                 default:
                     throw new Exception("数据库类型目前不支持！");
             }
         }

         /// <summary>
         /// 将数据加载到本地，在本地对数据进行操作
         /// </summary>
         /// <param name="Sql">Sql语句</param>
         /// <param name="parameter">参数化查询</param>
         /// <returns>返回从数据库中读取到的DataTable表</returns>
         public static DataTable ExecuteQuery(string Sql, params IDbDataParameter[] parameter)
         {
              using (IDbConnection conn=getConnection())
              using (IDbCommand cmd = conn.CreateCommand())
              {
                 conn.Open();
                 cmd.CommandText = Sql;
                 for (int i = ; i < parameter.Length; i++)
                 {
                     cmd.Parameters.Add(parameter[i]);
                 }
                 DataTable tab = new DataTable();
                 using (IDataReader reader = cmd.ExecuteReader())
                 {
                     tab.Load(reader);
                     return tab;
                 }
             }
         }
         /// <summary>
         /// 用于执行增加和删除语句
         /// </summary>
         /// <param name="Sql">Sql语句</param>
         /// <param name="parameter">参数化查询</param>
         /// <returns>有多少语句执行成功</returns>
         public static int ExecuteNonQuery(string Sql, params IDbDataParameter[] parameter)
         {
             using (IDbConnection conn = getConnection())
             using (IDbCommand cmd = conn.CreateCommand())
             {
                 conn.Open();
                 cmd.CommandText = Sql;
                 for (int i = ; i < parameter.Length; i++)
                 {
                     cmd.Parameters.Add(parameter[i]);
                 }
                 return cmd.ExecuteNonQuery();
             }
         }
         /// <summary>
         /// 执行语句后，返回第一行第一列的数据
         /// </summary>
         /// <param name="Sql"></param>
         /// <param name="parameter"></param>
         /// <returns>object类型的值</returns>
         public static object ExecuteScalar(string Sql, params IDbDataParameter[] parameter)
         {
             using (IDbConnection conn=getConnection())
              using (IDbCommand cmd = conn.CreateCommand())
              {
                 conn.Open();
                 cmd.CommandText = Sql;
                 for (int i = ; i < parameter.Length; i++)
                 {
                     cmd.Parameters.Add(parameter[i]);
                 }
                 return cmd.ExecuteScalar();
             }
         }
         /// <summary>
         /// 在数据库中，进行数据库的查询操作
         /// </summary>
         /// <param name="Sql"></param>
         /// <param name="parameter"></param>
         /// <returns></returns>
         public static IDataReader ExecuteReader(string Sql, params IDbDataParameter[] parameter)
         {
             using (IDbConnection conn = getConnection())
             using (IDbCommand cmd = conn.CreateCommand())
             {
                 conn.Open();
                 cmd.CommandText = Sql;
                 for (int i = ; i < parameter.Length; i++)
                 {
                     cmd.Parameters.Add(parameter[i]);
                 }
                 return cmd.ExecuteReader(CommandBehavior.CloseConnection);
             }
         }
     }
     /// <summary>
     /// 判断是什么数据库
     /// </summary>
     public class DBdatabase
     {
         public static DatabaseList database { get; set; }
     }
     public class AdoHelper
     {
         /// <summary>
         /// 将字符串转换成枚举类型
         /// </summary>
         /// <typeparam name="T">枚举类型</typeparam>
         /// <param name="value">字符串值</param>
         /// <returns></returns>
         public static T EnumParse<T>(string value)
         {
             return (T)Enum.Parse(typeof(T), value);
         }

         /// <summary>
         /// 对数据库进行操作
         /// </summary>
         /// <param name="conn">获取一个连接</param>
         /// <returns></returns>
         public static IDbCommand CreateCommand(IDbConnection conn)
         {
             IDbCommand cmd = conn.CreateCommand();
             conn.Open();
             return cmd;
         }
     }
     /// <summary>
     /// 数据库类型
     /// </summary>
     public enum DatabaseList
     {
         MYSQL = ,
         SQLSERVER =
     }