Python入门系列（十一）一篇搞定python操作MySQL数据库
2024-09-18 06:38:35
开始
安装MySQL驱动
$ python -m pip install mysql-connector-python
测试MySQL连接器
import mysql.connector
测试MySQL连接
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
password="yourpassword"
)
print(mydb)
创建数据库
import mysql.connector
mydb = mysql.connector.connect(
host="localhost",
user="yourusername",
password="yourpassword"
)
mycursor = mydb.cursor()
mycursor.execute("CREATE DATABASE mydatabase")
创建表格
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))")
插入数据
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！。注意这个语句：mydb.commit()。它是进行修改的必要条件，否则就不会对表进行修改。
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.")
获取插入的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)
查询
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)
从表格中选择
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：我们使用fetchall()方法，它从最后执行的语句中获取所有行。
选择列
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)
如果只想查询一条数据，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条件
使用筛选器选择
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)
通配符
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注入
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
对结果进行排序
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关键字对结果进行降序排序。
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)
删除记录
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注入
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")
删除表
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)
更新数据
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注入
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")
限制结果
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)
从另一个位置开始
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)
连接两张或更多数据表
# 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)
结束
MySQL的基本操作就是这样子了。
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