C#编程入门--SQLSERVER数据库帮助类

很值得学习的SQLDBHelper，供小型项目使用。
   
 public class SQLDBHelper
    {
        /// <summary>
        /// 连接数据库
        /// </summary>
        private static string connectionString = "Data Source=.; Initial Catalog=database; UID=sa;PASSWORD=123456;pooling=false; ";

        #region 设置数据库链接
        /// <summary>
        /// 设置数据库链接
        /// </summary>
        /// <param name="server"></param>
        /// <param name="database"></param>
        /// <param name="name"></param>
        /// <param name="pwd"></param>
        /// <param name="pool"></param>
        /// <returns></returns>
        public static bool SetConn(string server, string database, string name, string pwd, string pool)
        {
            connectionString = "Data Source=" + server
            + "; Initial Catalog=" + database
            + "; UID=" + name
            + ";PWD=" + pwd
            + "; pooling=" + pool + ";";
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                try
                {
                    conn.Open();
                    return true;
                }
                catch (Exception E)
                {
                    conn.Close();
                    return false;
                }
            }
        }
        #endregion

        #region 测试数据库链接
        /// <summary>
        /// 测试数据库链接
        /// </summary>
        /// <returns></returns>
        public static bool TestConn()
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                try
                {
                    conn.Open();
                    return true;
                }
                catch (Exception E)
                {
                    conn.Close();
                    return false;
                }
            }
        }
        #endregion

        #region 公用获取Connection
        /// <summary>
        /// //打开连接   并获得 SqlConnection
        /// </summary>
        public static SqlConnection Connection
        {
            get
            {
                SqlConnection conn = new SqlConnection(connectionString);
                if (conn == null)
                {
                    conn.Open();
                }
                else if (conn.State == System.Data.ConnectionState.Closed)
                {
                    conn.Open();
                }
                else if (conn.State == System.Data.ConnectionState.Broken)
                {
                    conn.Close();
                    conn.Open();
                }
                return conn;
            }
        }

        #endregion

        #region 公用方法
        /// <summary>
        /// 获取某表的某字段的最大值
        /// </summary>
        /// <param name="fieldName">字段名</param>
        /// <param name="tableName">表名</param>
        /// <returns></returns>
        public static int GetMaxID(string fieldName, string tableName)
        {
            string sqlString = "select max(" + fieldName + ")+1 from " + tableName;
            object obj = GetSingle(sqlString);
            if (obj == null)
            {
                return 1;
            }
            else
            {
                return int.Parse(obj.ToString());
            }
        }

        /// <summary>
        /// 查询某个值是否存在
        /// </summary>
        /// <param name="sqlString">sql</param>
        /// <param name="cmdParms">参数</param>
        /// <returns></returns>
        public static bool Exists(string sqlString, params SqlParameter[] cmdParms)
        {
            object obj = GetSingle(sqlString, cmdParms);
            int cmdResult;
            if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
            {
                cmdResult = 0;
            }
            else
            {
                cmdResult = int.Parse(obj.ToString());
            }
            if (cmdResult == 0)
            {
                return false;
            }
            else
            {
                return true;
            }
        }

        #endregion

        #region  执行简单SQL语句
        /// <summary>
        /// 执行SQL语句，返回影响的记录数
        /// </summary>
        /// <param name="sqlString">SQL语句</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string sqlString)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand(sqlString, connection))
                {
                    try
                    {
                        connection.Open();
                        int rows = cmd.ExecuteNonQuery();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        connection.Close();
                        throw new Exception(E.Message);
                    }
                    finally
                    {
                        cmd.Dispose();
                        connection.Close();
                    }
                }
            }
        }

        /// <summary>
        /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="sqlStringList">多条SQL语句</param>        
        public static void ExecuteSqlTran(ArrayList sqlStringList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                SqlCommand cmd = new SqlCommand();
                cmd.Connection = conn;
                SqlTransaction tx = conn.BeginTransaction();
                cmd.Transaction = tx;
                try
                {
                    for (int n = 0; n < sqlStringList.Count; n++)
                    {
                        string sqlString = sqlStringList[n].ToString();
                        if (sqlString.Trim().Length > 1)
                        {
                            cmd.CommandText = sqlString;
                            cmd.ExecuteNonQuery();
                        }
                    }
                    tx.Commit();
                }
                catch (System.Data.SqlClient.SqlException E)
                {
                    tx.Rollback();
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    conn.Close();
                }
            }
        }

        /// <summary>
        /// 执行带一个存储过程参数的的SQL语句。
        /// </summary>
        /// <param name="sqlString">SQL语句</param>
        /// <param name="content">参数内容,比如一个字段是格式复杂的文章，有特殊符号，可以通过这个方式添加</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSql(string sqlString, string content)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand(sqlString, connection);
                System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@content",
                    SqlDbType.NText);
                myParameter.Value = content;
                cmd.Parameters.Add(myParameter);
                try
                {
                    connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
                catch (System.Data.SqlClient.SqlException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

        /// <summary>
        /// 向数据库里插入图像格式的字段(和上面情况类似的另一种实例)
        /// </summary>
        /// <param name="sqlString">SQL语句</param>
        /// <param name="fs">图像字节,数据库的字段类型为image的情况</param>
        /// <returns>影响的记录数</returns>
        public static int ExecuteSqlInsertImg(string sqlString, byte[] fs)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand(sqlString, connection);
                System.Data.SqlClient.SqlParameter myParameter = new System.Data.SqlClient.SqlParameter("@fs",
                    SqlDbType.Image);
                myParameter.Value = fs;
                cmd.Parameters.Add(myParameter);
                try
                {
                    connection.Open();
                    int rows = cmd.ExecuteNonQuery();
                    return rows;
                }
                catch (System.Data.SqlClient.SqlException E)
                {
                    throw new Exception(E.Message);
                }
                finally
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

        /// <summary>
        /// 执行一条计算查询结果语句，返回查询结果（object）。
        /// </summary>
        /// <param name="sqlString">计算查询结果语句</param>
        /// <returns>查询结果（object）</returns>
        public static object GetSingle(string sqlString)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand(sqlString, connection))
                {
                    try
                    {
                        connection.Open();
                        object obj = cmd.ExecuteScalar();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        connection.Close();
                        throw new Exception(e.Message);
                    }
                    finally
                    {
                        cmd.Dispose();
                        connection.Close();
                    }
                }
            }
        }

        /// <summary>
        /// 执行查询语句，返回SqlDataReader
        /// </summary>
        /// <param name="sqlString">查询语句</param>
        /// <returns>SqlDataReader</returns>
        public static SqlDataReader ExecuteReader(string sqlString)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand(sqlString, connection);
            SqlDataReader myReader = null;
            try
            {
                connection.Open();
                myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                return myReader;
            }
            catch (System.Data.SqlClient.SqlException e)
            {
                connection.Close();
                throw new Exception(e.Message);
            }
            finally
            {
                if (myReader == null)
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

        /// <summary>
        /// 执行查询语句，返回DataSet
        /// </summary>
        /// <param name="sqlString">查询语句</param>
        /// <returns>DataSet</returns>
        public static DataSet GetDataSet(string sqlString)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                DataSet ds = new DataSet();
                try
                {
                    connection.Open();
                    SqlDataAdapter command = new SqlDataAdapter(sqlString, connection);
                    command.Fill(ds, "ds");
                }
                catch (System.Data.SqlClient.SqlException ex)
                {
                    throw new Exception(ex.Message);
                }
                finally
                {
                    connection.Close();
                }
                return ds;
            }
        }

        #endregion

        #region 执行带参数的SQL语句

        /// <summary>
        /// 
        /// </summary>
        /// <param name="sqlString"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static int ExecuteSql(string sqlString, params SqlParameter[] cmdParms)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, connection, null, sqlString, cmdParms);
                        int rows = cmd.ExecuteNonQuery();
                        cmd.Parameters.Clear();
                        return rows;
                    }
                    catch (System.Data.SqlClient.SqlException E)
                    {
                        throw new Exception(E.Message);
                    }
                    finally
                    {
                        cmd.Dispose();
                        connection.Close();
                    }
                }
            }
        }


        /// <summary>
        /// 执行多条SQL语句，实现数据库事务。
        /// </summary>
        /// <param name="sqlStringList">SQL语句的哈希表（key为sql语句，value是该语句的SqlParameter[]）</param>
        public static void ExecuteSqlTran(Hashtable sqlStringList)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                conn.Open();
                using (SqlTransaction trans = conn.BeginTransaction())
                {
                    SqlCommand cmd = new SqlCommand();
                    try
                    {
                        //循环
                        foreach (DictionaryEntry myDE in sqlStringList)
                        {
                            string cmdText = myDE.Key.ToString();
                            SqlParameter[] cmdParms = (SqlParameter[])myDE.Value;
                            PrepareCommand(cmd, conn, trans, cmdText, cmdParms);
                            int val = cmd.ExecuteNonQuery();
                            cmd.Parameters.Clear();

                            trans.Commit();
                        }
                    }
                    catch
                    {
                        trans.Rollback();
                        throw;
                    }
                    finally
                    {
                        conn.Close();
                    }
                }
            }
        }


        /// <summary>
        /// 执行SQL语句并返回单个值
        /// </summary>
        /// <param name="sqlString"></param>
        /// <param name="cmdParms"></param>
        /// <returns></returns>
        public static object GetSingle(string sqlString, params SqlParameter[] cmdParms)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                using (SqlCommand cmd = new SqlCommand())
                {
                    try
                    {
                        PrepareCommand(cmd, connection, null, sqlString, cmdParms);
                        object obj = cmd.ExecuteScalar();
                        cmd.Parameters.Clear();
                        if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                        {
                            return null;
                        }
                        else
                        {
                            return obj;
                        }
                    }
                    catch (System.Data.SqlClient.SqlException e)
                    {
                        throw new Exception(e.Message);
                    }
                    finally
                    {
                        cmd.Dispose();
                        connection.Close();
                    }
                }
            }
        }

        /// <summary>
        /// 获得查询的结果集
        /// </summary>
        public static SqlDataReader ExecuteReader(string sqlString, params SqlParameter[] cmdParms)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            SqlCommand cmd = new SqlCommand();
            SqlDataReader myReader = null;
            try
            {
                PrepareCommand(cmd, connection, null, sqlString, cmdParms);
                myReader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
                cmd.Parameters.Clear();
                return myReader;
            }
            catch (System.Data.SqlClient.SqlException e)
            {
                connection.Close();
                throw new Exception(e.Message);
            }
            finally
            {
                if (myReader == null)
                {
                    cmd.Dispose();
                    connection.Close();
                }
            }
        }

        /// <summary>
        /// 获得查询的数据集
        /// </summary>
        public static DataSet GetDataSet(string sqlString, params SqlParameter[] cmdParms)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand();
                PrepareCommand(cmd, connection, null, sqlString, cmdParms);
                using (SqlDataAdapter da = new SqlDataAdapter(cmd))
                {
                    DataSet ds = new DataSet();
                    try
                    {
                        da.Fill(ds, "ds");
                        cmd.Parameters.Clear();
                    }
                    catch (System.Data.SqlClient.SqlException ex)
                    {
                        throw new Exception(ex.Message);
                    }
                    finally
                    {
                        cmd.Dispose();
                        connection.Close();
                    }
                    return ds;
                }
            }
        }

        /// <summary>
        /// 装载SqlCommand对象
        /// </summary>
        private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, string cmdText,
            SqlParameter[] cmdParms)
        {
            if (conn.State != ConnectionState.Open)
            {
                conn.Open();
            }
            cmd.Connection = conn;
            cmd.CommandText = cmdText;
            if (trans != null)
            {
                cmd.Transaction = trans;
            }
            cmd.CommandType = CommandType.Text; //cmdType;
            if (cmdParms != null)
            {
                foreach (SqlParameter parm in cmdParms)
                {
                    cmd.Parameters.Add(parm);
                }
            }
        }

        #endregion

        #region 存储过程操作

        /// <summary>
        /// 执行存储过程,返回结果集
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlDataReader</returns>
        public static SqlDataReader RunProcedureForDataReader(string storedProcName, IDataParameter[] parameters)
        {
            SqlConnection connection = new SqlConnection(connectionString);
            try
            {
                SqlDataReader returnReader;
                connection.Open();
                SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
                command.CommandType = CommandType.StoredProcedure;
                returnReader = command.ExecuteReader(CommandBehavior.CloseConnection);
                return returnReader;
            }
            catch (System.Data.SqlClient.SqlException ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                connection.Close();
            }
        }

        /// <summary>
        /// 执行存储过程,返回数据集
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>DataSet</returns>
        public static DataSet RunProcedureForDataSet(string storedProcName, IDataParameter[] parameters)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                DataSet dataSet = new DataSet();
                connection.Open();
                SqlDataAdapter sqlDA = new SqlDataAdapter();
                sqlDA.SelectCommand = BuildQueryCommand(connection, storedProcName, parameters);
                sqlDA.Fill(dataSet);
                connection.Close();
                return dataSet;
            }
        }


        /// <summary>
        /// 构建 SqlCommand 对象(用来返回一个结果集，而不是一个整数值)
        /// </summary>
        /// <param name="connection">数据库连接</param>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <returns>SqlCommand</returns>
        private static SqlCommand BuildQueryCommand(SqlConnection connection, string storedProcName,
            IDataParameter[] parameters)
        {
            SqlCommand command = new SqlCommand(storedProcName, connection);
            command.CommandType = CommandType.StoredProcedure;
            foreach (SqlParameter parameter in parameters)
            {
                command.Parameters.Add(parameter);
            }
            return command;
        }

        /// <summary>
        /// 执行存储过程，返回影响的行数        
        /// </summary>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        /// <param name="rowsAffected">影响的行数</param>
        /// <returns></returns>
        public static int RunProcedure(string storedProcName, IDataParameter[] parameters, out int rowsAffected)
        {
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                try
                {
                    int result;
                    connection.Open();
                    SqlCommand command = BuildIntCommand(connection, storedProcName, parameters);
                    rowsAffected = command.ExecuteNonQuery();
                    result = (int)command.Parameters["ReturnValue"].Value;
                    return result;
                }
                catch (System.Data.SqlClient.SqlException ex)
                {
                    throw new Exception(ex.Message);
                }
                finally
                {
                    connection.Close();
                }
            }
        }

        /// <summary>
        /// 构建一个SqlCommand对象(用来返回一个整数值)
        /// </summary>
        /// <param name="connection">数据库连接</param>
        /// <param name="storedProcName">存储过程名</param>
        /// <param name="parameters">存储过程参数</param>
        private static SqlCommand BuildIntCommand(SqlConnection connection, string storedProcName,
            IDataParameter[] parameters)
        {
            SqlCommand command = BuildQueryCommand(connection, storedProcName, parameters);
            command.Parameters.Add(new SqlParameter("ReturnValue", SqlDbType.Int, 4, ParameterDirection.ReturnValue,
                false, 0, 0, string.Empty, DataRowVersion.Default, null));
            return command;
        }

        #endregion

        #region 执行SQL语句返回受影响行数

        /// <summary>
        /// 执行SQL语句返回受影响行数
        /// </summary>
        public static int ExecuteNonQuery(SqlTransaction transaction, string commandText,
            params SqlParameter[] commandParameters)
        {
            SqlCommand objCommand = new SqlCommand();
            PrepareCommand(objCommand, transaction.Connection, transaction, commandText, commandParameters);
            int iNum1 = objCommand.ExecuteNonQuery();
            objCommand.Parameters.Clear();
            return iNum1;
        }

        #endregion

    }