02 数据库应用sqlite3（1）

一、思路技术：SQLite3、

1、访问数据库的步骤

import sqlite3
con = sqlite3.connect('test.db')
cur = con.cursor()

cur.execute('create table category(id primary key, sort, name)')

cur.execute("insert into category values(1, 1, 'computer')")

cur.execute("insert into category values(?, ?, ?)", (2, 3, 'literature'))

cur.execute('select * from category')
print(cur.fetchall())
# 输出：[(1, 1, 'computer'), (2, 3, 'literature')]

for row in cur.execute('select * from category'):
    print(row[0], row[1])
1 1
2 3
    
con.commit() # 事务提交

con.rollback() # 事务回滚

cur.close()

con.close()

2、创建数据库和表

import sqlite3
con = sqlite3.connect('sales.db')
con.execute('create table book(id primary key, price, name)')

3、数据库的插入、更新和删除操作

import sqlite3
Con = sqlite3.connect('sales.db')
Cur = Con.cursor()

books = [('021', 25, '大学计算机'),
         ('022', 30, '大学英语'),
         ('023', 18, '艺术欣赏'),
         ('024', 35, '高级语言程序设计')]
         
Cur.execute("insert into book(id, price, name) values('001', 33, '大学计算机多媒体')")

Cur.execute("insert into book(id, price, name) values(?,?,?)", ('002', 28, '数据库基础'))

Cur.executemany('insert into book(id, price, name) values(?,?,?)', books)

Cur.execute('Update book set price=? where name = ?', (25, '大学英语'))

n = Cur.execute('delete from book where price = ?', (25,))
print('删除了',n.rowcount,'行记录')
Con.commit()
Cur.close()
Con.close()

删除了 2 行记录

4、数据库表的查询操作

import sqlite3
Con = sqlite3.connect('sales.db')
Cur = Con.cursor()

Cur.execute('select id, price, name from book')
for row in Cur:
    print(row)

(‘002’, 28, ‘数据库基础’)
(‘001’, 33, ‘大学计算机多媒体’)
(‘023’, 18, ‘艺术欣赏’)
(‘024’, 35, ‘高级语言程序设计’)