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;}?