我使用的是 Python 3.7.0
PostgreSQL可以使用psycopg2
模块与Python集成。
sycopg2
是用于Python编程语言的PostgreSQL数据库适配器。
psycopg2
是非常小,快速,稳定的。 您不需要单独安装此模块,因为默认情况下它会随着Python 2.5.x
版本一起发布。
pip3 install python-psycopg2
pip3 install psycopg2-binary
连接到数据库
以下Python代码显示了如何连接到现有的数据库。 如果数据库不存在,那么它将自动创建,最后将返回一个数据库对象。
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully")
在这里指定使用testdb
作为数据库名称,如果数据库已成功打开连接,则会提供以下消息:
Open database successfully
创建表
以下Python程序将用于在先前创建的数据库(testdb
)中创建一个表:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully") cur = conn.cursor() cur.execute('''CREATE TABLE COMPANY (ID INT PRIMARY KEY NOT NULL, NAME TEXT NOT NULL, AGE INT NOT NULL, ADDRESS CHAR(50), SALARY REAL);''') print "Table created successfully" conn.commit() conn.close()
当执行上述程序时,它将在数据库testdb
中创建COMPANY
表,并显示以下消息:
Opened database successfully
Table created successfully
插入操作
以下Python程序显示了如何在上述示例中创建的COMPANY
表中创建记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully") cur = conn.cursor() cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \ VALUES (1, 'Paul', 32, 'California', 20000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \ VALUES (2, 'Allen', 25, 'Texas', 15000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \ VALUES (3, 'Teddy', 23, 'Norway', 20000.00 )"); cur.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \ VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 )"); conn.commit() print("Records created successfully"); conn.close()
当执行上述程序时,它将在COMPANY
表中创建/插入给定的记录,并显示以下两行:
Opened database successfully
Records created successfully
SELECT操作
以下 Python 程序显示了如何从上述示例中创建的 COMPANY
表中获取和显示记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully") cur = conn.cursor() cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print("ID = ", row[0]) print("NAME = ", row[1]) print("ADDRESS = ", row[2]) print("SALARY = ", row[3], "\n") print("Operation done successfully"); conn.close()
执行上述程序时,会产生以下结果:
Opened database successfully ID = 1 NAME = Paul ADDRESS = California SALARY = 20000.0 ID = 2 NAME = Allen ADDRESS = Texas SALARY = 15000.0 ID = 3 NAME = Teddy ADDRESS = Norway SALARY = 20000.0 ID = 4 NAME = Mark ADDRESS = Rich-Mond SALARY = 65000.0 Operation done successfully
更新操作
以下 Python 代码显示了如何使用UPDATE
语句来更新任何记录,然后从COMPANY
表中获取并显示更新的记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully") cur = conn.cursor() cur.execute("UPDATE COMPANY set SALARY = 25000.00 where ID=1") conn.commit print("Total number of rows updated :", cur.rowcount) cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print("ID = ", row[0]) print("NAME = ", row[1]) print("ADDRESS = ", row[2]) print("SALARY = ", row[3], "\n") print("Operation done successfully"); conn.close()
Python
执行上述程序时,会产生以下结果:
Opened database successfully
Total number of rows updated : 1
ID = 1
NAME = Paul
ADDRESS = California
SALARY = 25000.0
ID = 2
NAME = Allen
ADDRESS = Texas
SALARY = 15000.0
ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000.0
ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000.0
Operation done successfully
删除操作
以下 Python 代码显示了如何使用 DELETE
语句来删除记录,然后从 COMPANY
表中获取并显示剩余的记录:
#!/usr/bin/python import psycopg2 conn = psycopg2.connect(database="testdb", user="postgres", password="pass123", host="127.0.0.1", port="5432") print("Opened database successfully") cur = conn.cursor() cur.execute("DELETE from COMPANY where ID=2;") conn.commit print("Total number of rows deleted :", cur.rowcount) cur.execute("SELECT id, name, address, salary from COMPANY") rows = cur.fetchall() for row in rows: print("ID = ", row[0]) print("NAME = ", row[1]) print("ADDRESS = ", row[2]) print("SALARY = ", row[3], "\n") print("Operation done successfully"); conn.close()
执行上述程序时,会产生以下结果:
Opened database successfully
Total number of rows deleted : 1
ID = 1
NAME = Paul
ADDRESS = California
SALARY = 20000.0
ID = 3
NAME = Teddy
ADDRESS = Norway
SALARY = 20000.0
ID = 4
NAME = Mark
ADDRESS = Rich-Mond
SALARY = 65000.0
Operation done successfully
https://www.yiibai.com/postgresql/postgresql_python.html