python操作mysql数据库
说明：这里仅仅为了演示python操作MySQL数据库，真实环境中，最好把CURD分别封装为对应的方法。并将这些方法在类中封装，体现python面向对象的特征。python链接MySQL数据库
建表
create database mydb;
use mydb;
create table EMP
(
EMPNO int(4) not null,
ENAME varchar(10),
JOB varchar(9),
MGR int(4),
HIREDATE date,
SAL int(7 ),
COMM int(7 ),
DEPTNO int(2)
);
alter table EMP add constraint PK_EMP primary key (EMPNO);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7369, 'SMITH', 'CLERK', 7902, str_to_date('17-12-1980', '%d-%m-%Y'), 800, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7499, 'ALLEN', 'SALESMAN', 7698, str_to_date('20-02-1981', '%d-%m-%Y'), 1600, 300, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7521, 'WARD', 'SALESMAN', 7698, str_to_date('22-02-1981', '%d-%m-%Y'), 1250, 500, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7566, 'JONES', 'MANAGER', 7839, str_to_date('02-04-1981', '%d-%m-%Y'), 2975, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7654, 'MARTIN', 'SALESMAN', 7698, str_to_date('28-09-1981', '%d-%m-%Y'), 1250, 1400, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7698, 'BLAKE', 'MANAGER', 7839, str_to_date('01-05-1981', '%d-%m-%Y'), 2850, null, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7782, 'CLARK', 'MANAGER', 7839, str_to_date('09-06-1981', '%d-%m-%Y'), 2450, null, 10);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7788, 'SCOTT', 'ANALYST', 7566, str_to_date('19-04-1987', '%d-%m-%Y'), 3000, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7839, 'KING', 'PRESIDENT', null, str_to_date('17-11-1981', '%d-%m-%Y'), 5000, null, 10);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7844, 'TURNER', 'SALESMAN', 7698, str_to_date('08-09-1981', '%d-%m-%Y'), 1500, 0, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7876, 'ADAMS', 'CLERK', 7788, str_to_date('23-05-1987', '%d-%m-%Y'), 1100, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7900, 'JAMES', 'CLERK', 7698, str_to_date('03-12-1981', '%d-%m-%Y'), 950, null, 30);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7902, 'FORD', 'ANALYST', 7566, str_to_date('03-12-1981', '%d-%m-%Y'), 3000, null, 20);
insert into EMP (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7934, 'MILLER', 'CLERK', 7782, str_to_date('23-01-1982', '%d-%m-%Y'), 1300, null, 10);
commit;
添加操作
# 导入mysql模块
import pymysql
# 链接数据库IP
host = "127.0.0.1"
# 数据库用户名
user = "root"
# 数据库密码
password = "admin"
# 数据库名
dbname = "mydb"
# 获取数据库连接
db = pymysql.connect(host=host, user=user, password=password, db=dbname)
# 调用cursor()方法创建一个对象cursor
cursor = db.cursor()
# SQL 插入语句
empno = 1111
eneme = "admin"
job = "CLERK"
mgr = 7788
sal = 3000
comm = 100
hiredate = "2000-09-09"
deptno = 10
# 注意数据库中的字符串需要使用单引号哦
sql = f"insert into emp(empno,ename,job,mgr,sal,comm,hiredate,deptno) \
values \
({empno},'{eneme}','{job}',{mgr},{sal},{comm},'{hiredate}',{deptno})"
print(sql)
try:
# 执行sql
cursor.execute(sql)
# 提交事务
db.commit()
except Exception as e:
print(e.args)
# 如有异常事务
db.rollback()
finally:
# 关闭资源
cursor.close()
db.close()
查询单条数据
import pymysql
host = "localhost"
user = "root"
password = "admin"
dbname = "mydb"
db = pymysql.connect(host=host, user=user, password=password, db=dbname)
cursor = db.cursor()
empno = 7788
sql = f"select * from emp where empno ={empno}"
try:
cursor.execute(sql)
# 返回单条数据,会将数据封装到元祖中
results = cursor.fetchone()
# 输出： (7788, 'SCOTT', 'ANALYST', 7566, datetime.date(1987, 4, 19), 3000, None, 20)
print(results)
except Exception as e:
# 异常处理
print(e.args)
finally:
# 关闭资源
cursor.close()
db.close()
查询多条数据
import pymysql
host = "localhost"
user = "root"
password = "admin"
dbname = "mydb"
db = pymysql.connect(host=host, user=user, password=password, db=dbname)
cursor = db.cursor()
deptno = 10
sql = f"select * from emp where deptno ={deptno}"
try:
cursor.execute(sql)
# 返回多条条数据,会将每条数据封装到元组中，多条数据又封装到元组中
results = cursor.fetchall()
# 遍历
for emp in results:
print(emp)
except Exception as e:
# 异常处理
print(e.args)
finally:
# 关闭资源
cursor.close()
db.close()
运行结果：
(1111, 'admin', 'CLERK', 7788, datetime.date(2000, 9, 9), 3000, 100, 10)
(7782, 'CLARK', 'MANAGER', 7839, datetime.date(1981, 6, 9), 2450, None, 10)
(7839, 'KING', 'PRESIDENT', None, datetime.date(1981, 11, 17), 5000, None, 10)
(7934, 'MILLER', 'CLERK', 7782, datetime.date(1982, 1, 23), 1300, None, 10)
修改操作
# 导入mysql模块
import pymysql
# 链接数据库IP
host = "127.0.0.1"
# 数据库用户名
user = "root"
# 数据库密码
password = "admin"
# 数据库名
dbname = "mydb"
# 获取数据库连接
db = pymysql.connect(host=host, user=user, password=password, db=dbname)
# 调用cursor()方法创建一个对象cursor
cursor = db.cursor()
# SQL 插入语句
empno = 1111
eneme = "ADMIN"
job = "MANGER"
mgr = 7788
sal = 4000
comm = 200
hiredate = "2000-10-10"
deptno = 10
# 注意数据库中的字符串需要使用单引号哦
sql = f"""
update emp set ename = '{eneme}',job = '{job}', mgr={mgr},sal={sal},comm={comm},hiredate ='{hiredate}',deptno={deptno}
where
empno = {empno}"""
try:
# 执行sql
cursor.execute(sql)
# 提交事务
db.commit()
except Exception as e:
print(e.args)
# 如有异常事务
db.rollback()
finally:
# 关闭资源
cursor.close()
db.close()
根据主键删除操作
# 导入mysql模块
import pymysql
# 链接数据库IP
host = "127.0.0.1"
# 数据库用户名
user = "root"
# 数据库密码
password = "admin"
# 数据库名
dbname = "mydb"
# 获取数据库连接
db = pymysql.connect(host=host, user=user, password=password, db=dbname)
# 调用cursor()方法创建一个对象cursor
cursor = db.cursor()
# SQL 语句
empno = 1111
sql = f"delete from emp where empno ={empno}"
try:
# 执行sql
cursor.execute(sql)
# 提交事务
db.commit()
except Exception as e:
print(e.args)
# 如有异常事务
db.rollback()
finally:
# 关闭资源
cursor.close()
db.close()