{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "abae549c-2d2f-486b-8868-e33495db47ce",
   "metadata": {},
   "source": [
    "# Dynamically Generated Query String\n",
    "\n",
    "### Since we embed SQL code in our Python programs as a string, we can dynamically generate the strings. This greatly enhances the flexibility of our code."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "8c2769b7-ab08-4ad8-af36-6257935e2508",
   "metadata": {},
   "outputs": [],
   "source": [
    "from DATA225utils import make_connection, dataframe_query"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ca63fa12-302c-4cbe-8335-038f15a78108",
   "metadata": {},
   "outputs": [],
   "source": [
    "def students_of(conn, first_name, last_name):\n",
    "    \"\"\"\n",
    "    Use the database connection conn to\n",
    "    return the students of the teacher\n",
    "    with the first and last names.\n",
    "    \"\"\"\n",
    "    # Generate the appropriate query string.\n",
    "    sql = ( \"\"\"\n",
    "            SELECT student.first, student.last, subject \n",
    "            FROM student, teacher, class, takes\n",
    "            \"\"\"\n",
    "          f\"WHERE teacher.last = '{last_name}' \"  # insert last name\n",
    "          f\"AND teacher.first = '{first_name}' \"  # insert first name\n",
    "            \"\"\"\n",
    "            AND teacher_id = teacher.id \n",
    "            AND code = class_code \n",
    "            AND student_id = student.id \n",
    "            ORDER BY subject, student.last\n",
    "            \"\"\"\n",
    "          )\n",
    "    \n",
    "    print(sql)\n",
    "    return dataframe_query(conn, sql)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "f0b2e68e-fa5c-4c0c-ab1f-6248d33897b0",
   "metadata": {},
   "outputs": [],
   "source": [
    "conn = make_connection('school.ini')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "02ef0e15-b577-4b45-a7ea-d89e105492e0",
   "metadata": {},
   "outputs": [],
   "source": [
    "first = 'John'\n",
    "last  = 'Lane'"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "fc9f52f9-ba34-41cf-947c-31a584e723a6",
   "metadata": {},
   "outputs": [],
   "source": [
    "print(f'Students of teacher {first} {last}:')\n",
    "\n",
    "count, students = students_of(conn, first, last)\n",
    "\n",
    "if count > 0:\n",
    "    display(students)\n",
    "else:\n",
    "    print('No students.')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ae113741-af4a-4336-93cb-1ad2709d15b6",
   "metadata": {},
   "outputs": [],
   "source": [
    "conn.close()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3aee9c4e-c23e-4c3b-b52c-da06cd144dc2",
   "metadata": {},
   "outputs": [],
   "source": [
    "# Copyright (c) 2023 by Ronald Mak"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3 (ipykernel)",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.9.13"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 5
}