pymysql实现增删改查的操作指南（python）

# 获取数据库连接对象
connection = pymysql.connect(host='localhost', port=3306, user='root', passwd='2732195202', db='book', charset='utf8')
# 获取一个游标
driver = connection.cursor()
# 执行一条sql
driver.execute("select version()")
# 获取执行sql的返回值
resultData=driver.fetchall()
print(resultData)

# 关闭数据库
connection.close()

import pymysql

#获取数据库连接对象
connection = pymysql.connect(host='localhost', port=3306, user='root', passwd='2732195202', db='book', charset='utf8')
#获取一个游标
driver=connection.cursor()
# 如果该数据库存在就删除
driver.execute("drop table if exists t_emp ")
# 定义sql语句
sql=""" CREATE TABLE `t_emp` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '主键',
  `department` varchar(20) DEFAULT NULL COMMENT '部门',
  `salary` decimal(10,2) DEFAULT NULL COMMENT '工资',
  `age` int(11) DEFAULT NULL COMMENT '年龄',
  `sex` varchar(4) DEFAULT NULL COMMENT '性别',
  PRIMARY KEY (`id`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8; 
    
"""
# 执行sql
driver.execute(sql)

# 关闭数据连接
connection.close()

# 获取数据库连接对象
connection=pymysql.connect(host='localhost',port=3306,user='root',passwd='2732195202',db='book',charset='utf8')

# 获取一个游标
driver=connection.cursor()

# 定义sql语句
sql=""" insert into t_emp(name,department,salary,age,sex)
        values("tom","开发部",8000,25,"男"), ("tom","开发部",8000,25,"男")
 
 """

# 尝试捕捉错误
try:
    # 执行SQL，并返回收影响行数
    result=driver.execute(sql)
    # 提交事务
    connection.commit()
    print("sql(insert)->error")
except:
    # 如果发生错误 则回滚事务
    print("sql(insert)->error")
    driver.rollback()
# 关闭数据库连接
connection.close()

#获取数据库连接对象 autocommit=True：设置数据库自动提交
connection=pymysql.connect(host="localhost",port=3306,user='root',passwd='2732195202',db='book',charset='utf8',autocommit=True)
# 获取游标对象
driver=connection.cursor()
# 定义sql
sql="update t_emp set salary=%s,name=%s where id=%s;"
# 如果sql错误就执行回滚操作，成功就提交
try:
    # 执行sql，并且返回影响的行数
    result=driver.execute(sql,[6000,"admin",19])
    connection.commit()
    print("sql（update）->success")
except:
    print("sql(update)->error")
    connection.rollback()

# 关闭数据库连接对象
connection.close()

# 获取数据库连接对象
connection=pymysql.connect(host='localhost',port=3306,user='root',passwd='2732195202',db='book',charset='utf8')
# 获取一个游标对象
driver=connection.cursor()
#定义sql
sql="select id, name, department, salary, age, sex from t_emp where id>%s and sex=%s"

# 只能获取一次，获取多次的时候会获取到null 如果是多个参数，需要传递一个元组
try:
    driver.execute(sql,(1,"女"))
    # 获取所有的查询结果 返回一个元组
    resultAll=driver.fetchall()
    print("resultAll:", resultAll)
    # 获取2条数据
    resultTwo=driver.fetchmany(2)
    print("resultTwo:", resultTwo)
    # 获取一条数据
    resultOne=driver.fetchone()
    print("resultThree:", resultOne)

    print("sql(select)->success")
except:
    connection.rollback()
    print("sql(select)->error")

# 关闭数据库连接
connection.close()

import  pymysql

# 获取数据库连接对象
connection = pymysql.connect(host='localhost', port=3306, user='root', passwd='2732195202', db='book', charset='utf8')
# 获取一个游标
driver = connection.cursor()
# 定义sql
sql="delete from t_emp where id=%s"

try:
    # 执行一条sql
    driver.execute(sql, (21))
    # 提交事务
    connection.commit()
    print("sql(delete)->success")
except  Exception as e:
    # 回滚事务
    connection.rollback()
    print("sql(delete)->error")
    print(e)

#关闭数据库连接
connection.close()