1.安装pymysql:pip install pymysql (在命令行窗口中执行)
2.卸载pymysql:pip uninstall pymysql (在命令行窗口中执行)
数据库的连接
需要注意的是port是不用引号括起来 charset是utf8不是utf-8
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# 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()
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创建数据库表
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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()
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向数据库中添加数据
1.需要注意的是规范sql,该写的字段都写上,不使用默认对应
2.提交事务的对象是数据库连接对象,而不是游标对象
3.pycharm连接mysql数据时,如果连接驱动是高版本,需要加上时区,jdbc:mysql://localhost/book?serverTimezone=GMT%2B8
4.如果主键是自动递增,则不能手动指定值,不能写该字段,让其自增长
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# 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()
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修改表中的数据
注意点:在操作数据库之前,需要确认是否获取连接数据库成功,并且选中了数库
2.卸载第三方库:pip uninstall pymysql
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#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()
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查询数据
1.项目中的.py文件不能和python库中的文件进行冲突,否则会出现异常
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# 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()
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删除表中的记录
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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()
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事务操作
提交事务: connection.commit()
回滚事务: connection.rollback()
总结
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原文链接:https://blog.csdn.net/m0_46188681/article/details/116721048