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Save a Row and Read It Back

This lesson creates a small table, saves one row in it and reads that row from a new connection. It follows Run Your First Query.

Before you start

You need what the earlier lessons set up:

  • first_query.py from Run Your First Query printed (2,), so the five connection values work;
  • the same folder and an active virtual environment (in a new terminal, run source .venv/bin/activate again).

This lesson creates a table named pycubrid_quickstart_notes for your user. Use the practice database or account from Before you start, not a production database.

Write the program

Create first_saved_row.py in the same folder. Put your own five values in SETTINGS if you do not use the Docker lab:

import pycubrid

SETTINGS = {"host": "localhost", "port": 33000, "database": "testdb", "user": "dba", "password": ""}

conn = pycubrid.connect(**SETTINGS)
cur = conn.cursor()

# 1. Create a table that belongs to this tutorial. The comment marks it, so the
#    cleanup script only ever drops this tutorial's own table.
cur.execute(
    "CREATE TABLE pycubrid_quickstart_notes (id INT PRIMARY KEY, note VARCHAR(100))"
    " COMMENT = 'created by the pycubrid quickstart'"
)
conn.commit()

# 2. Insert one row. The ? marks are filled with the values that follow, in order.
cur.execute(
    "INSERT INTO pycubrid_quickstart_notes (id, note) VALUES (?, ?)",
    (1, "my first saved row"),
)
conn.commit()  # commit makes the change permanent and visible to others
cur.close()
conn.close()

# 3. Check from a brand-new connection that the committed row was saved.
check = pycubrid.connect(**SETTINGS)
check_cur = check.cursor()
check_cur.execute("SELECT id, note FROM pycubrid_quickstart_notes ORDER BY id")
print("Rows seen by a new connection:", check_cur.fetchall())
check_cur.close()
check.close()

Run it

python first_saved_row.py

A second connection sees the saved row:

Rows seen by a new connection: [(1, 'my first saved row')]

What the program did

  • SETTINGS holds the five connection values once, and connect(**SETTINGS) passes them as keyword arguments, so both connections use the same values.
  • CREATE TABLE made the tutorial table. Its comment marks it as the tutorial's own, which Finish Safely checks before it drops anything.
  • The ? marks are placeholders: pycubrid replaces each one with the matching value from the tuple, safely escaped, before it sends the statement. Always pass values this way instead of pasting them into the SQL text yourself. Parameter Binding describes how each Python type is sent.
  • commit() makes the changes permanent. Until you commit, other connections do not see them. The new connection check proves that the row was saved.
  • fetchall() reads every remaining row of the result as a list of tuples.

If you run it again

Running the file a second time, or again after it was interrupted, stops at the first statement with Class dba.pycubrid_quickstart_notes already exists (the owner name, here dba, is your user). The table from the earlier run is still there. Do not drop it by hand: run the cleanup in Finish Safely, then run first_saved_row.py again.

Next step

The row is saved. Next, commit and roll back: add a second row and undo it before it is saved.