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📜  Python PostgreSQL-游标对象

📅  最后修改于: 2020-11-07 07:57:09             🧑  作者: Mango

psycopg库的Cursor类提供使用Python代码在数据库中执行PostgreSQL命令的方法。

使用它的方法，您可以执行SQL语句，从结果集中获取数据，调用过程。

您可以使用Connection对象/类的cursor()方法创建Cursor对象。

例

import psycopg2
#establishing the connection
conn = psycopg2.connect(
   database="mydb", user='postgres', password='password', host='127.0.0.1', port= '5432'
)

#Setting auto commit false
conn.autocommit = True

#Creating a cursor object using the cursor() method
cursor = conn.cursor()

方法

以下是Cursor类/对象提供的各种方法。

Sr.No. Methods & Description
1

callproc()

This method is used to call existing procedures PostgreSQL database.
2

close()

This method is used to close the current cursor object.
3

executemany()

This method accepts a list series of parameters list. Prepares an MySQL query and executes it with all the parameters.
4

execute()

This method accepts a MySQL query as a parameter and executes the given query.
5

fetchall()

This method retrieves all the rows in the result set of a query and returns them as list of tuples. (If we execute this after retrieving few rows it returns the remaining ones)
6

fetchone()

This method fetches the next row in the result of a query and returns it as a tuple.
7

fetchmany()

This method is similar to the fetchone() but, it retrieves the next set of rows in the result set of a query, instead of a single row.

物产

以下是Cursor类的属性-

Sr.No. Property & Description
1

description

This is a read only property which returns the list containing the description of columns in a result-set.
2

lastrowid

This is a read only property, if there are any auto-incremented columns in the table, this returns the value generated for that column in the last INSERT or, UPDATE operation.
3

rowcount

This returns the number of rows returned/updated in case of SELECT and UPDATE operations.
4

closed

This property specifies whether a cursor is closed or not, if so it returns true, else false.
5

connection

This returns a reference to the connection object using which this cursor was created.
6

name

This property returns the name of the cursor.
7

scrollable

This property specifies whether a particular cursor is scrollable.