Python入門系列（十一）一篇搞定python操作MySQL資料庫

開始

安裝MySQL驅動

$ python -m pip install mysql-connector-python

測試MySQL聯結器

import mysql.connector

測試MySQL連線

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword"
)

print(mydb)

建立資料庫

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword"
)

mycursor = mydb.cursor()

mycursor.execute("CREATE DATABASE mydatabase")

建立表格

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("CREATE TABLE customers (name VARCHAR(255), address VARCHAR(255))")

插入資料

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = ("John", "Highway 21")
mycursor.execute(sql, val)

mydb.commit()

print(mycursor.rowcount, "record inserted.")

重要！。注意這個語句：mydb.commit()。它是進行修改的必要條件，否則就不會對錶進行修改。

插入多行

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = [
  ('Peter', 'Lowstreet 4'),
  ('Amy', 'Apple st 652'),
  ('Hannah', 'Mountain 21'),
  ('Michael', 'Valley 345'),
  ('Sandy', 'Ocean blvd 2'),
  ('Betty', 'Green Grass 1'),
  ('Richard', 'Sky st 331'),
  ('Susan', 'One way 98'),
  ('Vicky', 'Yellow Garden 2'),
  ('Ben', 'Park Lane 38'),
  ('William', 'Central st 954'),
  ('Chuck', 'Main Road 989'),
  ('Viola', 'Sideway 1633')
]

mycursor.executemany(sql, val)

mydb.commit()

print(mycursor.rowcount, "was inserted.")

獲取插入的ID

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "INSERT INTO customers (name, address) VALUES (%s, %s)"
val = ("Michelle", "Blue Village")
mycursor.execute(sql, val)

mydb.commit()

print("1 record inserted, ID:", mycursor.lastrowid)

查詢

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM customers")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

從表格中選擇

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM customers")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

注意：我們使用fetchall()方法，它從最後執行的語句中獲取所有行。

選擇列

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT name, address FROM customers")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

如果只想查詢一條資料，可以使用fetchone()方法。

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM customers")

myresult = mycursor.fetchone()

print(myresult)

Where條件

使用篩選器選擇

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT * FROM customers WHERE address ='Park Lane 38'"

mycursor.execute(sql)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

萬用字元

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT * FROM customers WHERE address LIKE '%way%'"

mycursor.execute(sql)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

防止SQL隱碼攻擊

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT * FROM customers WHERE address = %s"
adr = ("Yellow Garden 2", )

mycursor.execute(sql, adr)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

Order By

對結果進行排序

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT * FROM customers ORDER BY name"

mycursor.execute(sql)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

使用DESC關鍵字對結果進行降序排序。

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT * FROM customers ORDER BY name DESC"

mycursor.execute(sql)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

刪除記錄

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "DELETE FROM customers WHERE address = 'Mountain 21'"

mycursor.execute(sql)

mydb.commit()

print(mycursor.rowcount, "record(s) deleted")

防止SQL隱碼攻擊

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "DELETE FROM customers WHERE address = %s"
adr = ("Yellow Garden 2", )

mycursor.execute(sql, adr)

mydb.commit()

print(mycursor.rowcount, "record(s) deleted")

刪除表

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "DROP TABLE customers"

mycursor.execute(sql)

更新資料

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")

防止SQL隱碼攻擊

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")

限制結果

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM customers LIMIT 5")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

從另一個位置開始

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

mycursor.execute("SELECT * FROM customers LIMIT 5 OFFSET 2")

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

連線兩張或更多資料表

# users 表
{ id: 1, name: 'John', fav: 154},
{ id: 2, name: 'Peter', fav: 154},
{ id: 3, name: 'Amy', fav: 155},
{ id: 4, name: 'Hannah', fav:},
{ id: 5, name: 'Michael', fav:}

# products
{ id: 154, name: 'Chocolate Heaven' },
{ id: 155, name: 'Tasty Lemons' },
{ id: 156, name: 'Vanilla Dreams' }

import mysql.connector

mydb = mysql.connector.connect(
  host="localhost",
  user="yourusername",
  password="yourpassword",
  database="mydatabase"
)

mycursor = mydb.cursor()

sql = "SELECT \
  users.name AS user, \
  products.name AS favorite \
  FROM users \
  INNER JOIN products ON users.fav = products.id"

mycursor.execute(sql)

myresult = mycursor.fetchall()

for x in myresult:
  print(x)

結束

MySQL的基本操作就是這樣子了。

您的關注，是我的無限動力!

公眾號 @生活處處有BUG