MySQL Connector/Python 開發人員指南  /  Connector/Python 教學  /  教學:使用緩衝游標提高員工薪資

6.1 教學:使用緩衝游標提高員工薪資

以下範例腳本將為所有在 2000 年加入公司且目前仍在職的員工,提供自明天起生效的 15% 加薪。

為了迭代選定的員工,我們使用緩衝游標。(緩衝游標在執行查詢後擷取並緩衝結果集的列;請參閱第 10.6.1 節,「cursor.MySQLCursorBuffered 類別」。)這樣一來,就不需要在新的變數中擷取列。相反地,游標可以當作迭代器使用。

注意

此腳本僅為範例;還有其他方法可以完成這個簡單的任務。

from __future__ import print_function

from decimal import Decimal
from datetime import datetime, date, timedelta

import mysql.connector

# Connect with the MySQL Server
cnx = mysql.connector.connect(user='scott', database='employees')

# Get two buffered cursors
curA = cnx.cursor(buffered=True)
curB = cnx.cursor(buffered=True)

# Query to get employees who joined in a period defined by two dates
query = (
  "SELECT s.emp_no, salary, from_date, to_date FROM employees AS e "
  "LEFT JOIN salaries AS s USING (emp_no) "
  "WHERE to_date = DATE('9999-01-01')"
  "AND e.hire_date BETWEEN DATE(%s) AND DATE(%s)")

# UPDATE and INSERT statements for the old and new salary
update_old_salary = (
  "UPDATE salaries SET to_date = %s "
  "WHERE emp_no = %s AND from_date = %s")
insert_new_salary = (
  "INSERT INTO salaries (emp_no, from_date, to_date, salary) "
  "VALUES (%s, %s, %s, %s)")

# Select the employees getting a raise
curA.execute(query, (date(2000, 1, 1), date(2000, 12, 31)))

# Iterate through the result of curA
for (emp_no, salary, from_date, to_date) in curA:

  # Update the old and insert the new salary
  new_salary = int(round(salary * Decimal('1.15')))
  curB.execute(update_old_salary, (tomorrow, emp_no, from_date))
  curB.execute(insert_new_salary,
               (emp_no, tomorrow, date(9999, 1, 1,), new_salary))

  # Commit the changes
  cnx.commit()

cnx.close()