Flash cards
Review the key moves
What is the main idea behind Python MySQL Update Table?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
___ mysql.connectorPut the learning moves in the order that makes the concept easiest to apply.
Update Table
You can update existing records in a table by using the "UPDATE" statement:
Example
Overwrite the address column from "Valley 345" to "Canyon 123":
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="
yourusername
",
password="
yourpassword
",
database="mydatabase"
)
mycursor =
mydb.cursor()
sql = "UPDATE customers SET address = 'Canyon 123'
WHERE address = 'Valley 345'"
mycursor.execute(sql)
mydb.commit()
print(mycursor.rowcount, "record(s) affected")Important!: Notice the statement: mydb.commit() . It is required to make the changes, otherwise no changes are made to the table.
Notice the WHERE clause in the UPDATE syntax: The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!
Prevent SQL Injection
It is considered a good practice to escape the values of any query, also in update statements.
This is to prevent SQL injections, which is a common web hacking technique to destroy or misuse your database.
The mysql.connector module uses the placeholder %s to escape values in the update statement:
Example
Escape values by using the placeholder %s method:
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="
yourusername
",
password="
yourpassword
",
database="mydatabase"
)
mycursor = mydb.cursor()
sql = "UPDATE customers SET address = %s
WHERE address = %s"
val = ("Valley 345", "Canyon 123")
mycursor.execute(sql,
val)
mydb.commit()
print(mycursor.rowcount, "record(s)
affected")