python-by-example-150-challenges/challenges139-145/sqlite-python-tutorial.py

import sqlite3
from sqlite3 import Error


"""""""""""""""""""   CREATING SQLITE DATABASE """""""""""""""""""""


def create_connection(db_file):
    """ create a database connection to the SQLite database
        specified by db_file
    :param db_file: database file
    :return: Connection object or None
    """
    try:
        conn = sqlite3.connect(db_file)
        return conn
    except Error as e:
        print(e)
    # finally:
    #     conn.close()
    return None


# if __name__ == '__main__':
#     create_connection('python-by-example.db')


""""""""""""""""     CREATE TABLE       """""""""""""""


def create_table(conn, create_table_sql):
    """ create a table from the create_table_sql statement
    :param conn: Connection object
    :param create_table_sql: a CREATE TABLE statement
    :return:
    """
    try:
        c = conn.cursor()
        c.execute(create_table_sql)
        c.close()
    except Error as e:
        print(e)


def create_project(conn, project):
    """
    Create a new project into the projects table
    :param conn:
    :param project:
    :return: project id
    """
    sql = ''' INSERT INTO projects(name,begin_date,end_date)
              VALUES(?,?,?) '''
    cur = conn.cursor()
    cur.execute(sql, project)
    cur.close()
    return cur.lastrowid


def create_task(conn, task):
    """
    Create a new task
    :param conn:
    :param task:
    :return:
    """

    sql = ''' INSERT INTO tasks(name,priority,status_id,project_id,begin_date,end_date)
              VALUES(?,?,?,?,?,?) '''
    cur = conn.cursor()
    cur.execute(sql, task)
    cur.close()
    return cur.lastrowid

def select_all_tasks(conn):
    """
    Query all rows in the tasks table
    :param conn: the Connection object
    :return:
    """
    cur = conn.cursor()
    cur.execute("SELECT * FROM tasks")

    rows = cur.fetchall()

    for row in rows:
        print(row)


def select_task_by_priority(conn, priority):
    """
    Query tasks by priority
    :param conn: the Connection object
    :param priority:
    :return:
    """
    cur = conn.cursor()
    cur.execute("SELECT * FROM tasks WHERE priority=?", (priority,))

    rows = cur.fetchall()

    for row in rows:
        print(row)


def update_task(conn, task):
    """
    update priority, begin_date, and end date of a task
    :param conn:
    :param task:
    :return: project id
    """
    sql = ''' UPDATE tasks
              SET priority = ? ,
                  begin_date = ? ,
                  end_date = ?
              WHERE id = ?'''
    cur = conn.cursor()
    cur.execute(sql, task)
    cur.close()


def delete_task(conn, task):
    """
    delete a task
    :param conn:
    :param task:
    :return: null
    """
    cur = conn.cursor()
    cur.execute(str("DELETE FROM tasks WHERE id = " + str(task)))
    cur.close()


def main():
    database = 'python-by-example.db'

    # sql_create_projects_table = """ CREATE TABLE IF NOT EXISTS projects (
    #                                     id integer PRIMARY KEY,
    #                                     name text NOT NULL,
    #                                     begin_date text,
    #                                     end_date text
    #                                 ); """
    #
    # sql_create_tasks_table = """CREATE TABLE IF NOT EXISTS tasks (
    #                                 id integer PRIMARY KEY,
    #                                 name text NOT NULL,
    #                                 priority integer,
    #                                 status_id integer NOT NULL,
    #                                 project_id integer NOT NULL,
    #                                 begin_date text NOT NULL,
    #                                 end_date text NOT NULL,
    #                                 FOREIGN KEY (project_id) REFERENCES projects (id)
    #                             );"""
    #
    # # create a database connection
    conn = create_connection(database)
    # if conn is not None:
    #     # create projects table
    #     create_table(conn, sql_create_projects_table)
    #     # create tasks table
    #     create_table(conn, sql_create_tasks_table)
    # else:
    #     print("Error! cannot create the database connection.")

    with conn:
            # # create a new project
            # project = ('Cool App with SQLite & Python', '2015-01-01', '2015-01-30');
            # project_id = create_project(conn, project)
            #
            # # tasks
            # task_1 = ('Analyze the requirements of the app', 1, 1, project_id, '2015-01-01', '2015-01-02')
            task_2 = ('Confirm with user about the top requirements', 1, 1, 1, '2015-01-03', '2015-01-05')
            #
            # # create tasks
            # create_task(conn, task_1)
            create_task(conn, task_2)


            # update_task(conn, (2, '2015-01-04', '2015-01-06',2))

            # delete_task(conn, 2)


            # print("1. Query task by priority:")
            # select_task_by_priority(conn, 1)
            #
            # print("2. Query all tasks")
            # select_all_tasks(conn)

if __name__ == '__main__':
    main()