c# 查看是否存在表

 
 
  public  bool IsTableExist(string tableName)
        {
            bool isTableExist = true;
            //try
            //{
               
 
                if (tableName == null)
                    throw new ArgumentNullException("table=null");
                this.Open();
 
                // SELECT count(*) FROM sqlite_master WHERE type='table' AND name='test';  
                SQLiteCommand cmd = new SQLiteCommand("SELECT count(*) as c FROM sqlite_master WHERE type='table' AND name=@tableName ");
                cmd.Connection = this.Connection;
                cmd.Parameters.Add(new SQLiteParameter("tableName", tableName));
                SQLiteDataReader reader = cmd.ExecuteReader();
                reader.Read();
                int c = reader.GetInt32(0);
                reader.Close();
                reader.Dispose();
                cmd.Dispose();
                //return false;  
                this.CloseQuietly();
                return c == 1;
 
 
                //string sql = "select count(*) FROM sqlite_master WHERE type='table' AND name=" + tableName;
                //SQLiteCommand command = new SQLiteCommand(sql, m_dbConnection);
                //SQLiteDataReader reader = command.ExecuteReader();
                //string qx_Str;
                //if (reader.HasRows)
                //{
 
                //    reader.Read();
                //    qx_Str = reader[0].ToString(); //出错位置
                //    if (qx_Str.Equals("0"))
                //    {
                //        isTableExist = false;
                //    }
                //    Console.WriteLine(qx_Str);
                //}
                //reader.Close();
                //command.Dispose();
              
              
            //}catch(Exception ex)
            //{
            //    MessageBox.Show(ex.Message);
            //}
            return isTableExist;
        }
 private void ConnectDatabase()
        {
            if (this.connection == null)
            {
                connection = new SQLiteConnection(@"Data source=" + path + "\db\local.db;Initial Catalog=sqlite;Integrated Security=True;Max Pool Size=10;");
                if (connection.State != ConnectionState.Open)
                {
                    connection.Open();
 
                }
                return;
            }
            connection = new SQLiteConnection(@"Data source=" + path + "\db\local.db;Initial Catalog=sqlite;Integrated Security=True;Max Pool Size=10;");
            if (connection.State != ConnectionState.Open)
            {
                connection.Open();
            }
        }
		
 
        //在指定数据库中创建一个table
 
        public  void CreateTable(string sqlStatement)
        {
            ConnectDatabase();
       
            //string sql = "create table local_batch_menu (node_text varchar(20),node_name varchar(50), sort int)";
            string sql = sqlStatement;
            SQLiteCommand command = new SQLiteCommand(sql,connection);
            //if (this.Connection.State == ConnectionState.Closed)
            //{
            //    this.Open();
            //}
              
            command.ExecuteNonQuery();
            command.Dispose();
            this.Connection.Close();
        }
		
		        public  DataSet ExecuteDataSet(string commandText)
        {
           // string sql = "select * from highscores order by score desc";
            // SQLiteCommand command = new SQLiteCommand(sql, connection);
            SQLiteCommand cmd = this.Connection.CreateCommand();
            cmd.CommandText = commandText;
            DataSet ds = new DataSet();
            if (this.Connection.State == ConnectionState.Closed)
                this.Open();
            SQLiteDataAdapter dataAdapter = new SQLiteDataAdapter(cmd);
 
 
            //  SQLiteDataAdapter da = new SQLiteDataAdapter(cmd);
            dataAdapter.Fill(ds);
            dataAdapter.Dispose();
            cmd.Dispose();
            this.CloseQuietly();
            return ds;
        }
		
		 //插入一些数据
        void fillTable()
        {
            string sql = "insert into highscores (name, score) values ('Me', 3000)";
            SQLiteCommand command = new SQLiteCommand(sql, connection);
            command.ExecuteNonQuery();
 
            sql = "insert into highscores (name, score) values ('Myself', 6000)";
            command = new SQLiteCommand(sql, connection);
            command.ExecuteNonQuery();
 
            sql = "insert into highscores (name, score) values ('And I', 9001)";
            command = new SQLiteCommand(sql, connection);
            command.ExecuteNonQuery();
        }
 
        //使用sql查询语句，并显示结果
        void printHighscores()
        {
            string sql = "select * from highscores order by score desc";
            SQLiteCommand command = new SQLiteCommand(sql, connection);
            SQLiteDataReader reader = command.ExecuteReader();
            while (reader.Read())
                Console.WriteLine("Name: " + reader["name"] + "	Score: " + reader["score"]);
            Console.ReadLine();
        }