Python操作PostgreSql数据库的方法(基本的增删改查)_Python

Python操作PostgreSql数据库（基本的增删改查）

操作数据库最快的方式当然是直接用使用SQL语言直接对数据库进行操作，但是偶尔我们也会碰到在代码中操作数据库的情况，我们可能用ORM类的库对数控库进行操作，但是当需要操作大量的数据时，ORM的数据显的太慢了。在python中，遇到这样的情况，我推荐使用psycopg2操作postgresql数据库

psycopg2

官方文档传送门： http://initd.org/psycopg/docs/index.html

简单的增删改查

连接

连接pg并创建表

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									PG_SQL_LOCAL = {

									 'database': 'postgres',

									 'user': 'postgres',

									 'password': "8dsa581",

									 # 'host':'10.27.78.1',

									 'host': 'localhost'

									}

									def connectPostgreSQL():

									 conn = psycopg2.connect(**PG_SQL_LOCAL)

									 print('connect successful!')

									 cursor = conn.cursor()

									 cursor.execute('''

									 create table public.members(

									 id integer not null primary key,

									 name varchar(32) not null,

									 password varchar(32) not null,

									 singal varchar(128)

									 )''')

									 conn.commit()

									 conn.close()

									 print('table public.member is created!')

增

一条一条的增加数据

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									def insertOperate():

									 conn = psycopg2.connect(**PG_SQL_LOCAL)

									 cursor = conn.cursor()

									 cursor.execute("insert into public.member(id,name,password,singal)\

									values(1,'member0','password0','signal0')")

									 cursor.execute("insert into public.member(id,name,password,singal)\

									values(2,'member1','password1','signal1')")

									 cursor.execute("insert into public.member(id,name,password,singal)\

									values(3,'member2','password2','signal2')")

									 cursor.execute("insert into public.member(id,name,password,singal)\

									values(4,'member3','password3','signal3')")

									 row = conn.fetchone()

									 print(row)

									 conn.commit()

									 conn.close()

									 print('insert records into public.memmber successfully')

查

fetchall() 一次性获取所有数据
fetchmany() 一次值提取2000条数据（使用服务端的游标）

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									def selectOperate():

									 conn = psycopg2.connect(**PG_SQL_LOCAL)

									 cursor = conn.cursor()

									 cursor.execute("select id,name,password,singal from public.member where id>2")

									 # rows = cursor.fetchall()

									 # for row in rows:

									 # print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3],)

									 while True:

									 rows = cursor.fetchmany(2000)

									 if not rows:

									  break

									 for row in rows:

									  # print('id=', row['id'], ',name=', row['name'], ',pwd=', row['pwd'], ',singal=', row['singal'],)

									  rid,name,pwd,singal = row

									  print(rid,name,pwd,singal)

									  # print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], )

									 conn.close()

改

更新数据

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									def updateOperate():

									 conn = psycopg2.connect(**PG_SQL_LOCAL)

									 cursor=conn.cursor()

									 result = cursor.execute("update public.member set name='member X' where id=3")

									 print(result)

									 conn.commit()

									 print("Total number of rows updated :", cursor.rowcount)

									 cursor.execute("select id,name,password,singal from public.member")

									 rows=cursor.fetchall()

									 for row in rows:

									 print('id=',row[0], ',name=',row[1],',pwd=',row[2],',singal=',row[3],'\n')

									 conn.close()

删

删除数据

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									def deleteOperate():

									 conn = psycopg2.connect(**PG_SQL_LOCAL)

									 cursor = conn.cursor()

									 cursor.execute("select id,name,password,singal from public.member")

									 rows = cursor.fetchall()

									 for row in rows:

									 print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], '\n')

									 print('begin delete')

									 cursor.execute("delete from public.member where id=2")

									 conn.commit()

									 print('end delete')

									 print("Total number of rows deleted :", cursor.rowcount)

									 cursor.execute("select id,name,password,singal from public.member")

									 rows = cursor.fetchall()

									 for row in rows:

									 print('id=', row[0], ',name=', row[1], ',pwd=', row[2], ',singal=', row[3], '\n')

									 conn.close()

补充，增加的字段带有时间格式

带有时间格式是，只需要传入时间格式的字符串（‘2017-05-27'）即可，PG会自动识别

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									cur.execute("INSERT INTO Employee "

									  "VALUES('Gopher', 'China Beijing', 100, '2017-05-27')")

									# 查询数据

									cur.execute("SELECT * FROM Employee")

									rows = cur.fetchall()

									for row in rows:

									 print('name=' + str(row[0]) + ' address=' + str(row[1]) +

									  ' age=' + str(row[2]) + ' date=' + str(row[3]), type(row[3]))

									 # 插入数据

									 sql = """INSERT INTO Employees VALUES(%s, %s, %s,%s) """

									 var = []

									 var.append([row[0], row[1], row[2], row[3]])

									 cur.executemany(sql, var)

									# 提交事务

									conn.commit()

									# 关闭连接

									conn.close()