Unit 2.4b Using Programs with Data, SQL
Using Programs with Data is focused on SQL and database actions. Part B focuses on learning SQL commands, connections, and curses using an Imperative programming style,
Database Programming is Program with Data
Each Tri 2 Final Project should be an example of a Program with Data.
Prepare to use SQLite in common Imperative Technique
- Explore SQLite Connect object to establish database connection- Explore SQLite Cursor Object to fetch data from a table within a database
Schema of Users table in Sqlite.db
Uses PRAGMA statement to read schema.
Describe Schema, here is resource Resource- What is a database schema?
-
What is the purpose of identity Column in SQL database?
-
What is the purpose of a primary key in SQL database?
-
What are the Data Types in SQL table?
import sqlite3
database = 'instance/sqlite.db' # this is location of database
def schema():
# Connect to the database file
conn = sqlite3.connect(database)
# Create a cursor object to execute SQL queries
cursor = conn.cursor()
# Fetch results of Schema
results = cursor.execute("PRAGMA table_info('football')").fetchall()
# Print the results
for row in results:
print(row)
# Close the database connection
conn.close()
schema()
# this makes the schema table from the sqlite database
Reading Users table in Sqlite.db
Uses SQL SELECT statement to read data
- What is a connection object? After you google it, what do you think it does?
- Same for cursor object?
- Look at conn object and cursor object in VSCode debugger. What attributes are in the object?
- Is "results" an object? How do you know?
import sqlite3
def read():
# Connect to the database file
conn = sqlite3.connect(database)
# Create a cursor object to execute SQL queries
cursor = conn.cursor()
# Execute a SELECT statement to retrieve data from a table
results = cursor.execute('SELECT * FROM football').fetchall()
# Print the results
if len(results) == 0:
print("Table is empty")
else:
for row in results:
print(row)
# Close the cursor and connection objects
cursor.close()
conn.close()
read()
# This reads the data in the sqlite database
import sqlite3
def create():
name = input("Enter your name:")
number = input("Enter your number:")
wins = input("Enter your wins:")
losses = input("Enter your losses:")
# Connect to the database file
conn = sqlite3.connect(database)
# Create a cursor object to execute SQL commands
cursor = conn.cursor()
try:
# Execute an SQL command to insert data into a table
cursor.execute("INSERT INTO football (_name, _number, _wins, _losses) VALUES (?, ?, ?, ?)", (name, number, wins, losses))
# Commit the changes to the database
conn.commit()
print(f"A new player record {name} has been created")
except sqlite3.Error as error:
print("Error while executing the INSERT:", error)
# Close the cursor and connection objects
cursor.close()
conn.close()
#create()
import sqlite3
def update():
name = input("Enter name to update")
number = input("Enter updated number")
wins = input("Enter updated wins")
losses = input("Enter updated losses")
# Connect to the database file
conn = sqlite3.connect(database)
# Create a cursor object to execute SQL commands
cursor = conn.cursor()
try:
# Execute an SQL command to update data in a table
cursor.execute("UPDATE football SET _number = ? WHERE _name = ?", (number, name))
cursor.execute("UPDATE football SET _wins = ? WHERE _name = ?", (wins, name))
cursor.execute("UPDATE football SET _losses = ? WHERE _name = ?", (losses, name))
if cursor.rowcount == 0:
# The uid was not found in the table
print(f"No name {name} was not found in the table")
else:
print(f"The row with user id {name} the password has been successfully updated")
conn.commit()
except sqlite3.Error as error:
print("Error while executing the UPDATE:", error)
# Close the cursor and connection objects
cursor.close()
conn.close()
#update()
import sqlite3
def delete():
name = input("Enter player name to delete")
# Connect to the database file
conn = sqlite3.connect(database)
# Create a cursor object to execute SQL commands
cursor = conn.cursor()
try:
cursor.execute("DELETE FROM football WHERE _name = ?", (name,))
if cursor.rowcount == 0:
# The uid was not found in the table
print(f"No name {name} was not found in the table")
else:
# The uid was found in the table and the row was deleted
print(f"The row with name {name} was successfully deleted")
conn.commit()
except sqlite3.Error as error:
print("Error while executing the DELETE:", error)
# Close the cursor and connection objects
cursor.close()
conn.close()
#delete()
def menu():
operation = input("Enter: (C)reate (R)ead (U)pdate or (D)elete or (S)chema")
if operation.lower() == 'c':
create()
elif operation.lower() == 'r':
read()
elif operation.lower() == 'u':
update()
elif operation.lower() == 'd':
delete()
elif operation.lower() == 's':
schema()
elif len(operation)==0: # Escape Key
return
else:
print("Please enter c, r, u, or d")
menu() # recursion, repeat menu
try:
menu() # start menu
except:
print("Perform Jupyter 'Run All' prior to starting menu")
Hacks
- Add this Blog to you own Blogging site. In the Blog add notes and observations on each code cell.
- In this implementation, do you see procedural abstraction? There's procedural abstraction in the CRUD functions and schema(). All of these functions are called in the menu command allowing for a more compact and efficient way of programming.
- In 2.4a or 2.4b lecture
- Do you see data abstraction? Complement this with Debugging example. The data is stored in a database which is called and being used throughout the program
- Use Imperative or OOP style to Create a new Table or do something that applies to your CPT project.
Reference... sqlite documentation