PostgreSQL自学笔记:与python交互

与python交互教程

原文地址:https://www.yiibai.com/html/postgresql/2013/080998.html

1. Python psycopg2 模块APIs

• 连接到数据库
  
  psycopg2.connect(database='test',user='postgres', password='520520',host='127.0.0.1',port='5432')

• 创建光标
  
  connection.cursor()

• 执行SQL语句
  
  cursor.execute(sql[,optional parameters])

• 提交当前事务
  
  connection.commit()

• 回滚
  
  connection.rollback()

• 关闭数据库
  
  connection.close()

• 提取查询结果的下一行
  
  cursor.fetchone()

• 取出下一组的查询结果的行数,返回一个列表
  
  cursor.fetchmany()

• 获取所有查询结果(剩余),返回一个列表
  
  cursor.fetchall()

2. 创建表

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database='test',user='postgres',
        password='520520',host='127.0.0.1',port='5432')

print('连接成功')

# 创建光标
cur = conn.cursor()

s = '''
create table pythonTest(
    e_no int primary key not null,
    e_name varchar(50) not null,
    e_gender char(2) not null,
    dept_no int not null,
    e_job varchar(100) not null,
    e_salary smallint,
    hireDate date
)
'''
cur.execute(s)
conn.commit()
print('建表成功')

conn.close()

3. 插入操作

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database='test',user='postgres',
        password='520520',host='127.0.0.1',port='5432')

print('连接成功')

# 创建光标
cur = conn.cursor()

s = '''
insert into pythonTest
    values(1001,'赵1','m',20,'会计',800,'2005-11-12'),
    (1002,'钱2','f',30,'推销员',1600,'2003-05-12'),
    (1003,'孙3','f',30,'推销员',1250,'2005-05-12'),
    (1004,'李4','m',20,'经理',2975,'1998-05-18'),
    (1005,'周5','m',30,'推销员',1250,'2001-06-12'),
    (1006,'吴6','f',30,'经理',2850,'1997-02-15'),
    (1007,'郑7','f',10,'经理',2450,'2002-09-12'),
    (1008,'王8','m',20,'分析师',3000,'2003-05-12'),
    (1009,'冯9','m',10,'董事长',5000,'1995-01-01'),
    (1010,'陈10','f',30,'推销员',1500,'1997-10-12'),
    (1011,'褚11','f',20,'会计',1100,'1999-10-05'),
    (1012,'卫12','m',30,'会计',950,'2008-06-15');
'''
cur.execute(s)
conn.commit()
print('插入成功')

conn.close()

4. 查询操作

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database='test',user='postgres',
        password='520520',host='127.0.0.1',port='5432')

print('连接成功')

# 创建光标
cur = conn.cursor()

s = '''
select e_name,e_job from pythonTest
'''
cur.execute(s)
conn.commit()

rows = cur.fetchall()
for i in rows:
    print(i)

conn.close()

5. 修改操作

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database='test',user='postgres',
        password='520520',host='127.0.0.1',port='5432')

print('连接成功')

# 创建光标
cur = conn.cursor()

s = '''
update pythonTest set e_job='分析师' where e_name='卫12'
'''
cur.execute(s)
conn.commit()
print('修改成功')

conn.close()

6. 删除操作

import psycopg2

# 连接到数据库
conn = psycopg2.connect(database='test',user='postgres',
        password='520520',host='127.0.0.1',port='5432')

print('连接成功')

# 创建光标
cur = conn.cursor()

s = '''
delete from pythonTest where e_no=1011
'''
cur.execute(s)
conn.commit()
print('删除成功')

conn.close()