Python MySQL – Update and Delete Data

To change or remove existing rows we use the SQL UPDATE and DELETE commands. Like INSERT, they need conn.commit() to save the change. We continue with the users table from the previous chapters.

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Update data

import mysql.connector

conn = mysql.connector.connect(
    host="localhost",
    user="root",
    password="",
    database="student"
)
cursor = conn.cursor()

sql = "UPDATE users SET mobile = %s WHERE id = %s"
values = ("9999999999", 1)

cursor.execute(sql, values)
conn.commit()

print(cursor.rowcount, "record updated")

cursor.close()
conn.close()

You can check the new value with a SELECT.

cursor.execute("SELECT name, mobile FROM users WHERE id = %s", (1,))
print(cursor.fetchone())

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Delete data

import mysql.connector

conn = mysql.connector.connect(
    host="localhost",
    user="root",
    password="",
    database="student"
)
cursor = conn.cursor()

sql = "DELETE FROM users WHERE id = %s"

cursor.execute(sql, (3,))
conn.commit()

print(cursor.rowcount, "record deleted")

cursor.close()
conn.close()

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Check the remaining rows

cursor.execute("SELECT id, name FROM users")
print(cursor.fetchall())

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Summary

• Use UPDATE ... SET ... WHERE to change rows and DELETE FROM ... WHERE to remove rows.
• Pass values with %s placeholders.
• Call conn.commit() after every change.
• cursor.rowcount shows how many rows were affected.
• Always write the WHERE condition.

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