[转载]DbHelper的常用数据库类

原文链接：http://hi.baidu.com/x2p2/blog/item/0492cad3c50a10d8a9ec9a1d.html

操作数据库是一个很麻烦的事情，下面是一个常用的依据工程原理的 DbHelper类

using System;
using System.Data;
using System.Data.Common;
using System.Configuration;
public class DbHelper
{
private static string dbProviderName = ConfigurationManager.AppSettings["DbHelperProvider"];
private static string dbConnectionString = ConfigurationManager.AppSettings["DbHelperConnectionString"];
private DbConnection connection;
public DbHelper()
{
this.connection = CreateConnection(DbHelper.dbConnectionString);
}
public DbHelper(string connectionString)
{
this.connection = CreateConnection(connectionString);
}
public static DbConnection CreateConnection()
{
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbConnection dbconn = dbfactory.CreateConnection();
dbconn.ConnectionString = DbHelper.dbConnectionString;
return dbconn;
}
public static DbConnection CreateConnection(string connectionString)
{
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbConnection dbconn = dbfactory.CreateConnection();
dbconn.ConnectionString = connectionString;
return dbconn;
}
public DbCommand GetStoredProcCommond(string storedProcedure)
{
DbCommand dbCommand = connection.CreateCommand();
dbCommand.CommandText = storedProcedure;
dbCommand.CommandType = CommandType.StoredProcedure;
return dbCommand;
}
public DbCommand GetSqlStringCommond(string sqlQuery)
{
DbCommand dbCommand = connection.CreateCommand();
dbCommand.CommandText = sqlQuery;
dbCommand.CommandType = CommandType.Text;
return dbCommand;
}
    #region 增加参数
    public void AddParameterCollection(DbCommand cmd, DbParameterCollection dbParameterCollection)
{
foreach (DbParameter dbParameter in dbParameterCollection)
{
cmd.Parameters.Add(dbParameter);
}
}
public void AddOutParameter(DbCommand cmd, string parameterName, DbType dbType, int size)
{
DbParameter dbParameter = cmd.CreateParameter();
dbParameter.DbType = dbType;
dbParameter.ParameterName = parameterName;
dbParameter.Size = size;
dbParameter.Direction = ParameterDirection.Output;
cmd.Parameters.Add(dbParameter);
}
public void AddInParameter(DbCommand cmd, string parameterName, DbType dbType, object value)
{
DbParameter dbParameter = cmd.CreateParameter();
dbParameter.DbType = dbType;
dbParameter.ParameterName = parameterName;
dbParameter.Value = value;
dbParameter.Direction = ParameterDirection.Input;
cmd.Parameters.Add(dbParameter);
}
public void AddReturnParameter(DbCommand cmd, string parameterName, DbType dbType)
{
DbParameter dbParameter = cmd.CreateParameter();
dbParameter.DbType = dbType;
dbParameter.ParameterName = parameterName;
dbParameter.Direction = ParameterDirection.ReturnValue;
cmd.Parameters.Add(dbParameter);
}
public DbParameter GetParameter(DbCommand cmd, string parameterName)
{
return cmd.Parameters[parameterName];
}

#endregion
    #region 执行
    public DataSet ExecuteDataSet(DbCommand cmd)
{
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbDataAdapter dbDataAdapter = dbfactory.CreateDataAdapter();
dbDataAdapter.SelectCommand = cmd;
DataSet ds = new DataSet();
dbDataAdapter.Fill(ds);
return ds;
}
public DataTable ExecuteDataTable(DbCommand cmd)
{
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbDataAdapter dbDataAdapter = dbfactory.CreateDataAdapter();
dbDataAdapter.SelectCommand = cmd;
DataTable dataTable = new DataTable();
dbDataAdapter.Fill(dataTable);
return dataTable;
}
public DbDataReader ExecuteReader(DbCommand cmd)
{
cmd.Connection.Open();
DbDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
return reader;
}
public int ExecuteNonQuery(DbCommand cmd)
{
cmd.Connection.Open();
int ret = cmd.ExecuteNonQuery();
cmd.Connection.Close();
return ret;
}
public object ExecuteScalar(DbCommand cmd)
{
cmd.Connection.Open();
object ret = cmd.ExecuteScalar();
cmd.Connection.Close();
return ret;
}
    #endregion
    #region 执行事务
    public DataSet ExecuteDataSet(DbCommand cmd, Trans t)
{
cmd.Connection = t.DbConnection;
cmd.Transaction = t.DbTrans;
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbDataAdapter dbDataAdapter = dbfactory.CreateDataAdapter();
dbDataAdapter.SelectCommand = cmd;
DataSet ds = new DataSet();
dbDataAdapter.Fill(ds);
return ds;
}
public DataTable ExecuteDataTable(DbCommand cmd, Trans t)
{
cmd.Connection = t.DbConnection;
cmd.Transaction = t.DbTrans;
DbProviderFactory dbfactory = DbProviderFactories.GetFactory(DbHelper.dbProviderName);
DbDataAdapter dbDataAdapter = dbfactory.CreateDataAdapter();
dbDataAdapter.SelectCommand = cmd;
DataTable dataTable = new DataTable();
dbDataAdapter.Fill(dataTable);
return dataTable;
}
public DbDataReader ExecuteReader(DbCommand cmd, Trans t)
{
cmd.Connection.Close();
cmd.Connection = t.DbConnection;
cmd.Transaction = t.DbTrans;
DbDataReader reader = cmd.ExecuteReader();
DataTable dt = new DataTable();
return reader;
}
public int ExecuteNonQuery(DbCommand cmd, Trans t)
{
cmd.Connection.Close();
cmd.Connection = t.DbConnection;
cmd.Transaction = t.DbTrans;
int ret = cmd.ExecuteNonQuery();
return ret;
}
public object ExecuteScalar(DbCommand cmd, Trans t)
{
cmd.Connection.Close();
cmd.Connection = t.DbConnection;
cmd.Transaction = t.DbTrans;
object ret = cmd.ExecuteScalar();
return ret;
}
    #endregion
}
public class Trans : IDisposable
{
private DbConnection conn;
private DbTransaction dbTrans;
public DbConnection DbConnection
{
get { return this.conn; }
}
public DbTransaction DbTrans
{
get { return this.dbTrans; }
}
public Trans()
{
conn = DbHelper.CreateConnection();
conn.Open();
dbTrans = conn.BeginTransaction();
}
public Trans(string connectionString)
{
conn = DbHelper.CreateConnection(connectionString);
conn.Open();
dbTrans = conn.BeginTransaction();
}
public void Commit()
{
dbTrans.Commit();
this.Colse();
}
public void RollBack()
{
dbTrans.Rollback();
this.Colse();
}
public void Dispose()
{
this.Colse();
}
public void Colse()
{
if (conn.State == System.Data.ConnectionState.Open)
{
conn.Close();
}
}
}


那么如何使用它呢?下面我给出一些基本的使用示例,基本能满足你大部分的数据库操作需要了.


1)直接执行sql语句


DbHelper db = new DbHelper();
DbCommand cmd = db.GetSqlStringCommond("insert t1 (id)values('haha')");
db.ExecuteNonQuery(cmd);


2)执行存储过程

DbHelper db = new DbHelper();
DbCommand cmd = db.GetStoredProcCommond("t1_insert");
db.AddInParameter(cmd, "@id", DbType.String, "heihei");
db.ExecuteNonQuery(cmd);


3)返回DataSet

DbHelper db = new DbHelper();
DbCommand cmd = db.GetSqlStringCommond("select * from t1");
DataSet ds = db.ExecuteDataSet(cmd);


4)返回DataTable

DbHelper db = new DbHelper();
DbCommand cmd = db.GetSqlStringCommond("t1_findall");
DataTable dt = db.ExecuteDataTable(cmd);


5)输入参数/输出参数/返回值的使用(比较重要哦)

DbHelper db = new DbHelper();
DbCommand cmd = db.GetStoredProcCommond("t2_insert");
db.AddInParameter(cmd, "@timeticks", DbType.Int64, DateTime.Now.Ticks);
db.AddOutParameter(cmd, "@outString", DbType.String, 20);
db.AddReturnParameter(cmd, "@returnValue", DbType.Int32);
db.ExecuteNonQuery(cmd);
string s = db.GetParameter(cmd, "@outString").Value as string;//out parameter
int r = Convert.ToInt32(db.GetParameter(cmd, "@returnValue").Value);//return value


6)DataReader使用

DbHelper db = new DbHelper();
DbCommand cmd = db.GetStoredProcCommond("t2_insert");
db.AddInParameter(cmd, "@timeticks", DbType.Int64, DateTime.Now.Ticks);
db.AddOutParameter(cmd, "@outString", DbType.String, 20);
db.AddReturnParameter(cmd, "@returnValue", DbType.Int32);
using (DbDataReader reader = db.ExecuteReader(cmd))
{
dt.Load(reader);
}
string s = db.GetParameter(cmd, "@outString").Value as string;//out parameter
int r = Convert.ToInt32(db.GetParameter(cmd, "@returnValue").Value);//return value

7)事务的使用.(项目中需要将基本的数据库操作组合成一个完整的业务流时,代码级的事务是必不可少的哦)

public void DoBusiness()
{
using (Trans t = new Trans())
{
try
{
D1(t);
throw new Exception();//如果有异常,会回滚滴
            D2(t);
t.Commit();
}
catch
{
t.RollBack();
}
}
}
public void D1(Trans t)
{
DbHelper db = new DbHelper();
DbCommand cmd = db.GetStoredProcCommond("t2_insert");
db.AddInParameter(cmd, "@timeticks", DbType.Int64, DateTime.Now.Ticks);
db.AddOutParameter(cmd, "@outString", DbType.String, 20);
db.AddReturnParameter(cmd, "@returnValue", DbType.Int32);
if (t == null)
db.ExecuteNonQuery(cmd);
else
db.ExecuteNonQuery(cmd, t);
string s = db.GetParameter(cmd, "@outString").Value as string;//out parameter
    int r = Convert.ToInt32(db.GetParameter(cmd, "@returnValue").Value);//return value
}
public void D2(Trans t)
{
DbHelper db = new DbHelper();
DbCommand cmd = db.GetSqlStringCommond("insert t1 (id)values('..')");
if (t == null)
db.ExecuteNonQuery(cmd);
else
db.ExecuteNonQuery(cmd, t);
}

以上我们好像没有指定数据库连接字符串,大家如果看下DbHelper的代码,就知道要使用它必须在config中配置两个参数,如下:

<appSettings>
<add key="DbHelperProvider" value="System.Data.SqlClient"/>
<add key="DbHelperConnectionString" value="Data Source=(local);Initial Catalog=DbHelperTest;Persist Security Info=True;User ID=sa;Password=sa"/>
</appSettings>