Pošiljanje poizvedb do podatkovne baze v Pythonu

Po povezavi z bazo podatkov ji lahko pošljemo poizvedbe. To naredimo s pomočjo spremenljivke query, v kateri zapišemo SQL poizvedbo za prikaz vseh podatkov iz tabele users. To spremenljivko moramo zapisati znotraj bloka s spremenljivko connection:

try:
	with connect(
			host='localhost',
			user='root',
			password='',
			database='test',
	) as connection:
		query = "SELECT * FROM users"
		
	except Error as e:
	print(e)

Nato zapišemo še eno konstrukcijo with za delo z MySQLConnection-objektom, shranjenim v spremenljivki connection. Na ta objekt moramo zaporedoma uporabiti posebne metode. Prva med njimi je metoda cursor, ki iz MySQLConnection-objekta ustvari CMySQLCursor-objekt. Nato na slednjega uporabimo metodo execute, ki izvede SQL poizvedbo, ki ji je posredovana kot parameter:

try:
	with connect(
		...
	) as connection:
		query = "SELECT * FROM users"
		with connection.cursor() as cursor:
			cursor.execute(query)

Nato moramo pridobiti vse podatke s pomočjo metode fetchall in jih shraniti v spremenljivko result. In za prikaz pridobljenih podatkov jih moramo obdelati z zanko for:

try:
	with connect(
		...
	) as connection:
		query = "SELECT * FROM users"
		with connection.cursor() as cursor:
			cursor.execute(query)
			result = cursor.fetchall()
			
			for row in result:
				print(row)

Popolna koda bo videti takole:

try:
with connect(
		host='localhost',
		user='root',
		password='',
		database='test',
) as connection:
	query = "SELECT * FROM users"
	with connection.cursor() as cursor:
		print(cursor)
		cursor.execute(query)
		result = cursor.fetchall()
		
		for row in result:
			print(row)
			
except Error as e:
print(e)

Po izvedbi kode se bodo v konzolo izpisali vsi zapisi v obliki n-terk:

(1, 'user1', 23, 400)
(2, 'user2', 25, 500)
(3, 'user3', 23, 500)
(4, 'user4', 30, 900)
(5, 'user5', 27, 500)
(6, 'user6', 28, 900)

Izpišite vse podatke iz tabele users.