SqlDbHelper备份，做项目时方便应用(目前不太全，把自己项目中的逐渐转移过来)

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这是官网新闻左侧类别那部分用到的

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public string ConnectionString = ConfigurationManager.ConnectionStrings["GsWebDbEntities"].ConnectionString;
public myDBHelper()
{
//
//TODO: 在此处添加构造函数逻辑
//
}

public DataSet ExecuteDataset(CommandType commandType, string commandText, params DbParameter[] commandParameters)
{

if ((this.ConnectionString == null) || (this.ConnectionString.Length == 0))
{
throw new ArgumentNullException("ConnectionString");
}
using (DbConnection connection = new SqlConnection(ConnectionString))
{
connection.ConnectionString = this.ConnectionString;
connection.Open();
return this.ExecuteDataset(connection, commandType, commandText, commandParameters);
}
}

public DataSet ExecuteDataset(DbConnection connection, CommandType commandType, string commandText, params DbParameter[] commandParameters)
{
if (connection == null)
{
throw new ArgumentNullException("connection");
}
DbCommand command = new SqlCommand();

this.PrepareCommand(command, connection, null, commandType, commandText, commandParameters);
using (DbDataAdapter adapter = new SqlDataAdapter())
{
adapter.SelectCommand = command;
DataSet dataSet = new DataSet();
DateTime now = DateTime.Now;
adapter.Fill(dataSet);
DateTime dtEnd = DateTime.Now;

command.Parameters.Clear();
if (connection.State==ConnectionState.Open)
{
connection.Close();
}

return dataSet;
}
}

private void PrepareCommand(DbCommand command, DbConnection connection, DbTransaction transaction, CommandType commandType, string commandText, DbParameter[] commandParameters)
{
if (command == null)
{
throw new ArgumentNullException("command");
}
if ((commandText == null) || (commandText.Length == 0))
{
throw new ArgumentNullException("commandText");
}
if (connection.State != ConnectionState.Open)
{

connection.Open();
}

command.Connection = connection;
command.CommandText = commandText;
if (transaction != null)
{
if (transaction.Connection == null)
{
throw new ArgumentException("The transaction was rollbacked or commited, please provide an open transaction.", "transaction");
}
command.Transaction = transaction;
}
command.CommandType = commandType;
if (commandParameters != null)
{

foreach (DbParameter parameter in commandParameters)
{
if (parameter != null)
{
if (((parameter.Direction == ParameterDirection.InputOutput) || (parameter.Direction == ParameterDirection.Input)) && (parameter.Value == null))
{
parameter.Value = DBNull.Value;
}
command.Parameters.Add(parameter);
}
}

}
}

*****************************************************************************以下来自网络，以上来自自己项目中的整理

using System;

using System.Data;

using System.Data.SqlClient;

 

namespace DbHelper

{

    public class SqlDbHelper

    {

        private SqlConnection conn;

        private SqlCommand cmd;

        private SqlDataReader reader;

        private SqlDataAdapter adapter;

        private string connectionString = @"server=.;database=student;uid=sa;pwd=scce";

 

        public string ConnectionString

        {

            get { return this.connectionString; }

            set { this.connectionString = value; }

        }

 

        /// <summary>

        /// 获取一个未打开连接的SqlConnection对象

        /// </summary>

        /// <returns>SqlConnection对象</returns>

        public SqlConnection GetConnection()

        {

            if (conn != null)

                return this.conn;

            return this.conn = new SqlConnection(connectionString);

        }

 

        /// <summary>

        /// 使用连接字符串获取未打开连接SqlConnection对象

        /// </summary>

        /// <param name="_connStr">连接字符串</param>

        /// <returns>SqlConnection对象</returns>

        public SqlConnection GetConnection(string _connStr)

        {

            if (this.conn != null)

                this.conn.ConnectionString = _connStr;

            else

                this.conn = new SqlConnection(_connStr);

            return this.conn;

        }

 

        /// <summary>

        /// 使用指定的Sql语句创建SqlCommand对象

        /// </summary>

        /// <param name="sqlStr">Sql语句</param>

        /// <returns>SqlCommand对象</returns>

        private SqlCommand GetCommand(string sqlStr)

        {

            if (this.conn == null)

                this.conn = GetConnection();

            if (this.cmd == null)

                this.cmd = this.GetCommand(sqlStr, CommandType.Text, null);

            else

            {

                this.cmd.CommandType = CommandType.Text;

                this.cmd.Parameters.Clear();

            }

            this.cmd.CommandText = sqlStr;

            return this.cmd;

        }

 

        /// <summary>

        /// 使用指定的Sql语句,CommandType,SqlParameter数组创建SqlCommand对象

        /// </summary>

        /// <param name="sqlStr">Sql语句</param>

        /// <param name="type">命令类型</param>

        /// <param name="paras">SqlParameter数组</param>

        /// <returns>SqlCommand对象</returns>

        public SqlCommand GetCommand(string sqlStr, CommandType type, SqlParameter[] paras)

        {

            if (conn == null)

                this.conn = this.GetConnection();

            if (cmd == null)

                this.cmd = conn.CreateCommand();

            this.cmd.CommandType = type;

            this.cmd.CommandText = sqlStr;

            this.cmd.Parameters.Clear();

            if (paras != null)

                this.cmd.Parameters.AddRange(paras);

            return this.cmd;

        }

 

        /// <summary>

        /// 执行Sql语句返回受影响的行数

        /// </summary>

        /// <param name="sqlStr">Sql语句</param>

        /// <returns>受影响的行数,失败则返回-1</returns>

        public int ExecuteNoQuery(string sqlStr)

        {

            int line = -1;

            CheckArgs(sqlStr);

            try { OpenConn(); line = this.ExecuteNonQuery(sqlStr,CommandType.Text,null); }

            catch (SqlException e) { throw e; }

            return line;

        }

 

        /// <summary>

        /// 使用指定的Sql语句,CommandType,SqlParameter数组执行Sql语句,返回受影响的行数

        /// </summary>

        /// <param name="sqlStr">Sql语句</param>

        /// <param name="type">命令类型</param>

        /// <param name="paras">SqlParameter数组</param>

        /// <returns>受影响的行数</returns>

        public int ExecuteNonQuery(string sqlStr, CommandType type, SqlParameter[] paras)

        {

            int line = -1;

            CheckArgs(sqlStr);

            if (this.cmd == null)

                GetCommand(sqlStr, type, paras);

            this.cmd.Parameters.Clear();

            this.cmd.CommandText = sqlStr;

            this.cmd.CommandType = type;

            if(paras != null)

                this.cmd.Parameters.AddRange(paras);

            try { OpenConn(); line = this.cmd.ExecuteNonQuery(); }

            catch (SqlException e) { throw e; }

            return line;

        }

 

        /// <summary>

        /// 使用指定Sql语句获取dataTable

        /// </summary>

        /// <param name="sqlStr">Sql语句</param>

        /// <returns>DataTable对象</returns>

        public DataTable GetDataTable(string sqlStr)

        {

            CheckArgs(sqlStr);

            if (this.conn == null)

                this.conn = GetConnection();

            this.adapter = new SqlDataAdapter(sqlStr, this.conn);

            DataTable table = new DataTable();

            try { adapter.Fill(table); }

            catch (SqlException e) { throw e; }

            return table;

        }

 

        /// <summary>

        /// 使用指定的Sql语句获取SqlDataReader

        /// </summary>

        /// <param name="sqlStr">sql语句</param>

        /// <returns>SqlDataReader对象</returns>

        public SqlDataReader GetSqlDataReader(string sqlStr)

        {

            CheckArgs(sqlStr);

            if (cmd == null)

                GetCommand(sqlStr);

            if(reader != null)

                reader.Dispose();

            try { OpenConn(); this.reader = this.cmd.ExecuteReader(); }

            catch (SqlException e) { throw e; }

            return this.reader;

        }

 

        /// <summary>

        /// 使用事务执行多条Sql语句

        /// </summary>

        /// <param name="sqlCommands">sql语句数组</param>

        /// <returns>全部成功则返回true否则返回false</returns>

        public bool ExecuteSqls(string[] sqlCommands)

        {

            if (sqlCommands == null)

                throw new ArgumentNullException();

            if(this.cmd == null)

                GetCommand(null);

            SqlTransaction tran = null;

            try

            {

                OpenConn();

                tran = this.conn.BeginTransaction();

                this.cmd.Transaction = tran;

                foreach (string sql in sqlCommands)

                {

                    if (ExecuteNoQuery(sql) == 0)

                    { tran.Rollback(); return false; }

                }

            }

            catch (SqlException e)

            {

                if(tran != null)

                    tran.Rollback();

                throw e;

            }

            tran.Commit();

            return true;

        }

 

        private void OpenConn()

        {

            try

            {

                if (this.conn.State == ConnectionState.Closed)

                    conn.Open();

            }

            catch (SqlException e) { throw e; }

        }

 

        private void CheckArgs(string sqlStr)

        {

            if (sqlStr == null)

                throw new ArgumentNullException();

            if (sqlStr.Length == 0)

                throw new ArgumentOutOfRangeException();

        }

 

    }

}