python sqlite3 增删改查(最基本的增删改查)

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话不多说

一、创建数据库和建表happy

'''导入sqlite3库'''
import sqlite3

'''创建数据库'''
conn = sqlite3.connect('demo.db')  #demo.db不存在时在py同一目录下自动创建demo.db

'''创建游标'''
cursor = conn.cursor()

'''建表'''
create_table_sql = '''create table happy(
         username text,
         password text,
         id int)'''

cursor.execute(create_table_sql)  #执行这个语句

'''关闭连接'''
conn.commit()
cursor.close()

二、插入数据：执行语句即可

username = "ytouch"
password = "123456"
user_id = 1

insert_data_sql = '''insert into happy
(username,password,id)
values 
(:st_name,:st_username,:st_id)'''

cursor.execute(insert_data_sql,{'st_name':username,'st_username':password,'st_id':user_id})

三、修改数据：执行以下语句就可以

update_sql = 'update happy set password = ? where username = ?'
cursor.execute(update_sql,("4578623","ytouch"))

四、查询数据:执行以下语句就可以

'''查询语句'''
search_sql = "select username,password from happy"

'''执行语句'''
results = cursor.execute(search_sql)

'''遍历打印输出'''
all_results  = results.fetchall()
for happys in all_results:
    print(type(happys))  #type:tuple
    print(happys)

五、删除数据

1.删除指定数据

delete_sql = 'delete from happy where id = 25'

2.删除一整个表格

delete_all_sql = 'drop table happy' #删除一整个表格