Python3 notes

查询数据

查询数据使用 SELECT 语句：

demo_mysql_test.py:

importmysql.connectormydb = mysql.connector.connect(  host="localhost",   user="root",   passwd="123456",   database="runoob_db")mycursor = mydb.cursor()mycursor.execute("SELECT * FROM sites")myresult = mycursor.fetchall()     # fetchall() 获取所有记录forxinmyresult:   print(x)

执行代码，输出结果为：

(1,'RUNOOB','https://www.runoob.com')

(2,'Google','https://www.google.com')

(3,'Github','https://www.github.com')

(4,'Taobao','https://www.taobao.com')

(5,'stackoverflow','https://www.stackoverflow.com/')

(6,'Zhihu','https://www.zhihu.com')

也可以读取指定的字段数据：

demo_mysql_test.py:

importmysql.connectormydb = mysql.connector.connect(  host="localhost",   user="root",   passwd="123456",   database="runoob_db")mycursor = mydb.cursor()mycursor.execute("SELECT name, url FROM sites")myresult = mycursor.fetchall()forxinmyresult:   print(x)

执行代码，输出结果为：

('RUNOOB','https://www.runoob.com')

('Google','https://www.google.com')

('Github','https://www.github.com')

('Taobao','https://www.taobao.com')

('stackoverflow','https://www.stackoverflow.com/')

('Zhihu','https://www.zhihu.com')

如果我们只想读取一条数据，可以使用 fetchone() 方法：

demo_mysql_test.py:

importmysql.connectormydb = mysql.connector.connect(  host="localhost",   user="root",   passwd="123456",   database="runoob_db")mycursor = mydb.cursor()mycursor.execute("SELECT * FROM sites")myresult = mycursor.fetchone()print(myresult)

执行代码，输出结果为：

(1,'RUNOOB','https://www.runoob.com')