Notebooks/02_PostgreSQL.ipynb

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   "cell_type": "markdown",
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   "source": [
    "## Introduction to Databases\n",
    "\n",
    "### Accessing Relational Databases - PostgreSQL"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import os\n",
    "import sys\n",
    "import time\n",
    "import datetime\n",
    "import numpy as np\n",
    "import pandas as pd\n",
    "import pathlib\n",
    "import getpass\n",
    "\n",
    "import psycopg2"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Acessing [PostgreSQL](https://www.psycopg.org/docs/)   "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "p = getpass.getpass()\n",
    "try:\n",
    "    conn = psycopg2.connect(\"dbname='testdb' user='rsouza' host='localhost' password='{}'\".format(p))\n",
    "except:\n",
    "    print(\"I am unable to connect to the database\")\n",
    "cur = conn.cursor()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "cur.execute('SELECT * FROM postgres LIMIT 2;')\n",
    "for r in cur.fetchall():\n",
    "   print(r)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#### Using Pandas"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "p = getpass.getpass()\n",
    "try:\n",
    "    conn = psycopg2.connect(\"dbname='postgres' user='rsouza' host='localhost' password='{}'\".format(p))\n",
    "except:\n",
    "    print(\"I am unable to connect to the database\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "df_postgres = psql.read_sql('SELECT * FROM postgres LIMIT 5;', con=conn)\n",
    "df_postgres.head()"
   ]
  }
 ],
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