Python接入MySQL实现增删改查的实战记录

execute(query, args=None)
# query为字符串类型的sql语句
# args：可选的序列或映射，用于query的参数值。
# 如果args为序列，query中必须使用%s做占位符；
# 如果args为映射，query中必须使用%(key)s做占位符

import pymysql
db = pymysql.connect('localhost', 'root', "password")  # 打开数据库连接，password替换为本机数据库密码
cursor = db.cursor()
cursor.execute('drop database learning;')
cursor.execute('create database learning;')
cursor.execute('use learning')
sql_create = """create table houses (name VARCHAR(100) NOT NULL, house_location VARCHAR(100) NOT NULL, purchasing_year VARCHAR(100) NOT NULL);"""
cursor.execute(sql_create)

# 插入
sql_insert = """insert into houses values(%s,%s,%s);"""
cursor.execute(sql_insert,('梦璃','南天门',1995))  # 插入单条数据
cursor.executemany(sql_insert,[('紫英','蜀山',1996),('天河','石沉',1997),('菱纱','溪洞',1998)])  # 插入多条数据

sql_select = """select * from houses"""
# 单条查询
cursor.execute(sql_select)
while 1:
 result = cursor.fetchone()
 if result is None:
  # 取完所有结果
  break
 print(result)

# 多条查询，取3条数据
cursor.execute(sql_select)
Result = cursor.fetchmany(3)
for res in Result:
 print(res)

# 多条查询，取所有数据
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)

# 更新一条数据
sql_update = """update houses set purchasing_year=2000 where name='菱纱';"""
cursor.execute(sql_update)
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)
# 更新多条数据
sql_update = """update houses set purchasing_year=%s where name=%s;"""
cursor.executemany(sql_update,[(2018,'梦璃'),(2019,'紫英')])
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)
# 回滚事务
db.rollback()
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)

# 删除1条数据
sql_delete = """delete from houses where name='梦璃';"""
cursor.execute(sql_delete)
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)
# 删除多条数据
sql_delete = """delete from houses where name=%s;"""
cursor.executemany(sql_delete,[('天河'),('紫英')])
cursor.execute(sql_select)
Result = cursor.fetchall()
for res in Result:
 print(res)

cursor.close()           # 关闭游标
db.commit()
db.close()            # 关闭数据库连接
print('sql执行成功')