一个仿PetShop的通用DBHelper类

今天参考PetShop的SqlHelper写了个更通用的DBHelper,兼容大部分DB.感觉对于小型开发来说,使用这样的通用类,更换DB会方便.奉上代码:

Code
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.Common;
using System.Configuration;

namespace MBDone.Core.DBUtility
{
    public static class DBHelper
    {
        private static readonly string connStringName = ConfigurationManager.AppSettings["connStringName"].ToString();
        private static readonly string connString = ConfigurationManager.ConnectionStrings[connStringName].ConnectionString;
        private static readonly string providerName = ConfigurationManager.ConnectionStrings[connStringName].ProviderName;
        public static DbProviderFactory provider = DbProviderFactories.GetFactory(providerName);

        #region Public Mothods

        public static int ExcuteNonQuery(string cmdText, params DbParameter[] cmdParms)
        {
            return ExcuteNonQuery(null, CommandType.Text, cmdText, cmdParms);
        }

        public static int ExcuteNonQuery(CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            return ExcuteNonQuery(null, cmdType, cmdText, cmdParms);
        }

        public static int ExcuteNonQuery(DbTransaction trans, CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            using (DbConnection conn = provider.CreateConnection())
            {
                using (DbCommand cmd = provider.CreateCommand())
                {
                    PrepareCommand(cmd, conn, trans, cmdType, cmdText, cmdParms);
                    return cmd.ExecuteNonQuery();
                }
            }
        }

        public static DbDataReader ExecuteReader(string cmdText, params DbParameter[] cmdParms)
        {
            return ExecuteReader(null, CommandType.Text, cmdText, cmdParms);
        }

        public static DbDataReader ExecuteReader(CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            return ExecuteReader(null, cmdType, cmdText, cmdParms);
        }

        public static DbDataReader ExecuteReader(DbTransaction trans, CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            DbConnection conn = provider.CreateConnection();
            DbCommand cmd = provider.CreateCommand();

            try
            {
                PrepareCommand(cmd, conn, trans, cmdType, cmdText, cmdParms);
                return cmd.ExecuteReader(CommandBehavior.CloseConnection);
            }
            catch
            {
                conn.Close();
                cmd.Dispose();
                throw;
            }
        }

        public static object ExecuteScalar(string cmdText, params DbParameter[] cmdParms)
        {
            return ExecuteScalar(null, CommandType.Text, cmdText, cmdParms);
        }

        public static object ExecuteScalar(CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            return ExecuteScalar(null, cmdType, cmdText, cmdParms);
        }

        public static object ExecuteScalar(DbTransaction trans, CommandType cmdType, string cmdText, params DbParameter[] cmdParms)
        {
            using (DbConnection conn = provider.CreateConnection())
            {
                using (DbCommand cmd = provider.CreateCommand())
                {
                    PrepareCommand(cmd, conn, trans, cmdType, cmdText, cmdParms);
                    return cmd.ExecuteScalar();
                }
            }
        }

        #endregion

        #region Private Methods

        private static void PrepareCommand(DbCommand cmd, DbConnection conn, DbTransaction trans, CommandType cmdType, string cmdText, DbParameter[] cmdParms)
        {
            conn.ConnectionString = connString;
            if (conn.State != ConnectionState.Open)
                conn.Open();

            cmd.Connection = conn;
            cmd.CommandText = cmdText;

            if (trans != null)
                cmd.Transaction = trans;

            cmd.CommandType = cmdType;

            if (cmdParms != null)
            {
                foreach (DbParameter parm in cmdParms)
                    cmd.Parameters.Add(parm);
            }
        }

        #endregion
    }
}

使用如下:

Code
string sql1 = "Delete From [User] Where [Id]=@Id";
DbParameter param = DBHelper.provider.CreateParameter();
param.ParameterName = "@Id";
param.Value = 3;
DbParameter[] ps = { param };
int count = DBHelper.ExcuteNonQuery(sql2, ps);

string sql2 = "SELECT TOP 100 [Id],[Name] FROM [User]";
DbDataReader dr = DBHelper.ExecuteReader(sql2, null);
while (dr.Read())
{
string name = dr[1].ToString();
}
dr.Close();

Web.config配置使用哪一种DB:(由上而下分别是Access,SQL server,SQLite)

Code
<appSettings>
    <add key="connStringName" value="defaultConnectionString1"/>
</appSettings>
<connectionStrings>
    <add name="defaultConnectionString1" connectionString="Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|\UserDB.mdb;Jet OLEDB:Database Password=1234567" providerName="System.Data.OleDb"/>
    <add name="defaultConnectionString2" connectionString="Data Source=10.152.86.42;Initial Catalog=UserDB;Persist Security Info=False;User ID=sa; pwd = 1234567" providerName="System.Data.SqlClient"/>
    <add name="defaultConnectionString3" connectionString="Data Source=|DataDirectory|\UserDB.s3db;Version=3;BinaryGUID=False;" providerName="System.Data.SQLite"/>
</connectionStrings>

注意如果使用SQLite除了引用"System.Data.SQLite.DLL"(在 http://sourceforge.net/projects/sqlite-dotnet2 下载 ADO.NET 2.0 Provider。找到下载包中的 System.Data.SQLite.DLL 拷贝到程序 Bin 目录。)

还必须配置DB Provider:

Code
<system.data>
    <DbProviderFactories>
        <remove invariant="System.Data.SQLite"/>
        <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".Net Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite"/>
    </DbProviderFactories>
</system.data>

否则会报错:

Code
Unable to find the requested .Net Framework Data Provider. It may not be installed.

注:本文基于WebApp开发而讲述.