Python 操作 PostgreSQL 資料庫
阿新 • • 發佈:2020-07-29
PostgreSQL可以使用psycopg2
模組與Python整合。
sycopg2
是用於Python程式語言的PostgreSQL資料庫介面卡。
psycopg2
是非常小,快速,穩定的。 您不需要單獨安裝此模組,因為預設情況下它會隨著Python 2.5.x
版本一起釋出。
pip3 install python-psycopg2
pip3 install psycopg2-binary
連線到資料庫
以下Python程式碼顯示瞭如何連線到現有的資料庫。 如果資料庫不存在,那麼它將自動建立,最後將返回一個數據庫物件。
#!/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")
在這裡指定使用testdb
作為資料庫名稱,如果資料庫已成功開啟連線,則會提供以下訊息:
Open database successfully
建立表
以下Python程式將用於在先前建立的資料庫(testdb
)中建立一個表:
#!/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()
當執行上述程式時,它將在資料庫testdb
中建立COMPANY
表,並顯示以下訊息:
Opened database successfully
Table created successfully
插入操作
以下Python程式顯示瞭如何在上述示例中建立的COMPANY
表中建立記錄:
#!/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()
當執行上述程式時,它將在COMPANY
表中建立/插入給定的記錄,並顯示以下兩行:
Opened database successfully
Records created successfully
SELECT操作
以下 Python 程式顯示瞭如何從上述示例中建立的COMPANY
表中獲取和顯示記錄:
#!/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()
執行上述程式時,會產生以下結果:
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 程式碼顯示瞭如何使用UPDATE
語句來更新任何記錄,然後從COMPANY
表中獲取並顯示更新的記錄:
#!/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
執行上述程式時,會產生以下結果:
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
刪除操作
以下 Python 程式碼顯示瞭如何使用DELETE
語句來刪除記錄,然後從COMPANY
表中獲取並顯示剩餘的記錄:
#!/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()
執行上述程式時,會產生以下結果:
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