Notebooks/08.ipynb

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   "source": [
    "# Views in SQL\n",
    "---\n",
    "\n",
    "A `view` is nothing more than a SQL statement that is stored in the database with an associated name. A view is actually a composition of a table in the form of a predefined SQL query.\n",
    "\n",
    "A view can contain all rows of a table or select rows from a table. A view can be created from one or many tables which depends on the written SQL query to create a view.\n",
    "\n",
    "Views, which are a type of virtual tables allow users to do the following −\n",
    "- Structure data in a way that users or classes of users find natural or intuitive.\n",
    "- Restrict access to the data in such a way that a user can see and (sometimes) modify exactly what they need and no more.\n",
    "- Summarize data from various tables which can be used to generate reports."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Connecting with the database"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "%load_ext sql\n",
    "# replace with your own credentials\n",
    "%sql ibm_db_sa://my-username:my-password@dashdb-txn-sbox-yp-dal09-03.services.dal.bluemix.net:50000/BLUDB"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " * ibm_db_sa://lzv55210:***@dashdb-txn-sbox-yp-dal09-12.services.dal.bluemix.net:50000/BLUDB\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "    <tr>\n",
       "        <th>country</th>\n",
       "        <th>first_name</th>\n",
       "        <th>last_name</th>\n",
       "        <th>test_score</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>United States</td>\n",
       "        <td>Marshall</td>\n",
       "        <td>Bernadot</td>\n",
       "        <td>54</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>United States</td>\n",
       "        <td>Celinda</td>\n",
       "        <td>Malkin</td>\n",
       "        <td>51</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Ukraine</td>\n",
       "        <td>Guillermo</td>\n",
       "        <td>Furze</td>\n",
       "        <td>53</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Ukraine</td>\n",
       "        <td>Aharon</td>\n",
       "        <td>Tunnow</td>\n",
       "        <td>48</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Russia</td>\n",
       "        <td>Bail</td>\n",
       "        <td>Goodwin</td>\n",
       "        <td>46</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Poland</td>\n",
       "        <td>Cole</td>\n",
       "        <td>Winteringham</td>\n",
       "        <td>49</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Sweden</td>\n",
       "        <td>Emlyn</td>\n",
       "        <td>Erricker</td>\n",
       "        <td>55</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Russia</td>\n",
       "        <td>Cathee</td>\n",
       "        <td>Sivewright</td>\n",
       "        <td>49</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Poland</td>\n",
       "        <td>Barny</td>\n",
       "        <td>Ingerson</td>\n",
       "        <td>57</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Sweden</td>\n",
       "        <td>Sharla</td>\n",
       "        <td>Papaccio</td>\n",
       "        <td>55</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Romania</td>\n",
       "        <td>Alina</td>\n",
       "        <td>Smolyar</td>\n",
       "        <td>52</td>\n",
       "    </tr>\n",
       "</table>"
      ],
      "text/plain": [
       "[('United States', 'Marshall', 'Bernadot', 54),\n",
       " ('United States', 'Celinda', 'Malkin', 51),\n",
       " ('Ukraine', 'Guillermo', 'Furze', 53),\n",
       " ('Ukraine', 'Aharon', 'Tunnow', 48),\n",
       " ('Russia', 'Bail', 'Goodwin', 46),\n",
       " ('Poland', 'Cole', 'Winteringham', 49),\n",
       " ('Sweden', 'Emlyn', 'Erricker', 55),\n",
       " ('Russia', 'Cathee', 'Sivewright', 49),\n",
       " ('Poland', 'Barny', 'Ingerson', 57),\n",
       " ('Sweden', 'Sharla', 'Papaccio', 55),\n",
       " ('Romania', 'Alina', 'Smolyar', 52)]"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%sql select * from STUDENTS"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 1. Creating a view"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " * ibm_db_sa://lzv55210:***@dashdb-txn-sbox-yp-dal09-12.services.dal.bluemix.net:50000/BLUDB\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[]"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%%sql\n",
    "create view view_1\n",
    "as select first_name, test_score from \n",
    "STUDENTS where country='Russia'"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 2. Displaying the view"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " * ibm_db_sa://lzv55210:***@dashdb-txn-sbox-yp-dal09-12.services.dal.bluemix.net:50000/BLUDB\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "    <tr>\n",
       "        <th>first_name</th>\n",
       "        <th>test_score</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Bail</td>\n",
       "        <td>46</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Cathee</td>\n",
       "        <td>49</td>\n",
       "    </tr>\n",
       "</table>"
      ],
      "text/plain": [
       "[('Bail', 46), ('Cathee', 49)]"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%sql select * from view_1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 3. Updating the view"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " * ibm_db_sa://lzv55210:***@dashdb-txn-sbox-yp-dal09-12.services.dal.bluemix.net:50000/BLUDB\n",
      "1 rows affected.\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/html": [
       "<table>\n",
       "    <tr>\n",
       "        <th>first_name</th>\n",
       "        <th>test_score</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Bail</td>\n",
       "        <td>46</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "        <td>Cathee</td>\n",
       "        <td>50</td>\n",
       "    </tr>\n",
       "</table>"
      ],
      "text/plain": [
       "[('Bail', 46), ('Cathee', 50)]"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%%sql\n",
    "update view_1 set test_score=50 where first_name='Cathee';\n",
    "select * from view_1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 4. Droping the view"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      " * ibm_db_sa://lzv55210:***@dashdb-txn-sbox-yp-dal09-12.services.dal.bluemix.net:50000/BLUDB\n",
      "Done.\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "[]"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "%sql drop view view_1"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Thanks for reading :)\n",
    "Created by [Tarun Kamboj](https://www.linkedin.com/in/kambojtarun/)."
   ]
  }
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