Python连接PostgreSQL数据库并查询数据的详细指南

pip install psycopg2-binary

pip3 install psycopg2-binary

import psycopg2

# 连接数据库的参数
dbname = "your_dbname"
user = "your_username"
password = "your_password"
host = "your_host"
port = "your_port"

# 连接字符串
conn_string = f"host={host} port={port} dbname={dbname} user={user} password={password}"

# 建立连接
conn = psycopg2.connect(conn_string)

# 创建cursor对象
cursor = conn.cursor()

# 要执行的SQL查询
query = "SELECT * FROM your_table_name;"

# 执行查询
cursor.execute(query)

# 获取查询结果
results = cursor.fetchall()

# 打印结果
for row in results:
    print(row)

for row in results:
    print(f"ID: {row[0]}, Name: {row[1]}")

# 获取列名
columns = [desc[0] for desc in cursor.description]

# 使用列名访问数据
for row in results:
    print(f"ID: {row[columns.index('id')]}, Name: {row[columns.index('name')]}")

# 插入数据
insert_query = "INSERT INTO your_table_name (column1, column2) VALUES (%s, %s);"
cursor.execute(insert_query, (value1, value2))

# 更新数据
update_query = "UPDATE your_table_name SET column1 = %s WHERE column2 = %s;"
cursor.execute(update_query, (new_value1, condition_value2))

# 删除数据
delete_query = "DELETE FROM your_table_name WHERE column1 = %s;"
cursor.execute(delete_query, (condition_value1,))

# 提交事务
conn.commit()

# 关闭cursor
cursor.close()

# 关闭连接
conn.close()

try:
    conn = psycopg2.connect(conn_string)
    cursor = conn.cursor()
    # 执行数据库操作...
except psycopg2.Error as e:
    print(f"Database error: {e}")
finally:
    if conn is not None:
        conn.close()