数据库助手类

引用命名空间：

private SqlConnection conn = null;private SqlCommand cmd = null;private SqlDataAdapter sda = null;private DataSet ds = null;//构造函数定义连接字符串public SqlHelper(){    string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;    conn = new SqlConnection(connStr);}//打开连接private SqlConnection getconn(){    if (conn.State == ConnectionState.Closed)    {        conn.Open();    }    return conn;}/// <summary>执行带参数的增删改sql语句或存储过程/// /// </summary>/// <param name="cmdText">增删改sql语句或存储过程</param>/// <param name="paras">参数成员</param>/// <returns>受影响行数</returns>public int ExecuteNonQuery(string cmdText, SqlParameter[] paras, CommandType ct){    int i;    try    {        //执行存储过程命令        cmd = new SqlCommand(cmdText, getconn());        //cmd访问类型        cmd.CommandType = ct;        //传递存储过程参数        cmd.Parameters.AddRange(paras);        //返回受影响行数        i = cmd.ExecuteNonQuery();    }    catch (Exception ex)    {        throw ex;    }    finally    {        conn.Close();    }    return i;}/// <summary>执行带参数的查询sql语句或存储过程/// /// </summary>/// <param name="cmdText">查询的sql语句或存储过程</param>/// <param name="paras">参数成员</param>/// <returns>返回查询表</returns>public DataTable ExecuteQuery(string cmdText, SqlParameter[] paras, CommandType ct){    DataTable dt = new DataTable();    try    {        //执行存储过程命令        cmd = new SqlCommand(cmdText, getconn());        //cmd访问类型        cmd.CommandType = ct;        //传递存储过程参数        cmd.Parameters.AddRange(paras);        //读取数据        sda = new SqlDataAdapter(cmd);        //填充数据表        ds = new DataSet();        sda.Fill(ds);        dt = ds.Tables[0];    }    catch (Exception ex)    {        throw ex;    }    finally    {        conn.Close();    }    return dt;}/// <summary> 执行不带参数的查询sql语句或存储过程(方法重载)////// </summary>/// <param name="cmdText">查询的sql语句或存储过程</param>/// <returns>返回数据表</returns>public DataTable ExecuteQuery(string cmdText, CommandType ct){    DataTable dt = new DataTable();    try    {        //执行存储过程命令        cmd = new SqlCommand(cmdText, getconn());        //cmd访问类型        cmd.CommandType = ct;        //读取数据        sda = new SqlDataAdapter(cmd);        //填充数据表        ds = new DataSet();        sda.Fill(ds);        dt = ds.Tables[0];    }    catch (Exception ex)    {        throw ex;    }    finally    {        conn.Close();    }    return dt;}/// <summary>执行带参数的返回受影响行数的sql语句或存储过程/// /// </summary>/// <param name="cmdText">sql语句或存储过程</param>/// <param name="paras">参数成员</param>/// <returns>返回受影响行数</returns>public int ExecuteScalar(string cmdText, SqlParameter[] paras, CommandType ct){    int i;    try    {        //执行存储过程命令        cmd = new SqlCommand(cmdText, getconn());        //cmd访问类型        cmd.CommandType = ct;        //传递存储过程参数        cmd.Parameters.AddRange(paras);        //返回受影响行数        i = (int)cmd.ExecuteScalar();    }    catch (Exception ex)    {        throw ex;    }    finally    {        conn.Close();    }    return i;}/// <summary>执行不带参数的返回受影响行数的sql语句或存储过程（方法重载）/// /// </summary>/// <param name="cmdText">sql语句或存储过程</param>/// <param name="paras">参数成员</param>/// <returns>返回行数</returns>public int ExecuteScalar(string cmdText, CommandType ct){    int i;    try    {        cmd = new SqlCommand(cmdText, getconn());        //cmd访问类型        cmd.CommandType = ct;        //返回受影响行数        i = (int)cmd.ExecuteScalar();    }    catch (Exception ex)    {        throw ex;    }    finally    {        conn.Close();    }    return i;}

?