Question

我有SQL连接并命名为db_connection我每周运行

tran= pd.read_sql('SELECT order_id, p.user_id, p.barcode, title, o.timestamp, amount, p.name, qty FROM transactions t left join orders o on t.order_id = o.id left join products p on t.product_id = p.id where date(o.timestamp)<=\'2017-09-27\' and date(o.timestamp)>=\'2017-09-21\' and p.user_id = \'63165\' ', con=db_connection)

tran2= pd.read_sql('SELECT order_id, p.user_id, p.barcode, title, o.timestamp, amount, p.name, qty FROM transactions t left join orders o on t.order_id = o.id left join products p on t.product_id = p.id where date(o.timestamp)<=\'2017-09-27\' and date(o.timestamp)>=\'2017-09-21\' and p.user_id = \'62345\' ', con=db_connection)

...

tran22= pd.read_sql('SELECT order_id, p.user_id, p.barcode, title, o.timestamp, amount, p.name, qty FROM transactions t left join orders o on t.order_id = o.id left join products p on t.product_id = p.id where date(o.timestamp)<=\'2017-09-27\' and date(o.timestamp)>=\'2017-09-21\' and p.user_id = \'78345\' ', con=db_connection)

例如，我想将所有日期更改为date(o.timestamp)<=\'2017-10-04\' and date(o.timestamp)>=\'2017-09-28\'，但这需要时间并且容易出错。是否有任何解决方案使日期只被调用一次？

Answer 1

的Python

虚拟解决方案是使用占位符以便编辑单个条目：

start = # evaluate or hardcode date
end = # evaluate or hardcode date

tran = pd.read_sql('... where date(o.timestamp)<=\'{END}\' and date(o.timestamp)>=\'{START}\' ...'.format(START=start, END=end), con=db_connection)
...
tran1 = ...

熊猫的参数

start = # evaluate or hardcode date
end= # evaluate or hardcode date
tran = pd.read_sql('... where date(o.timestamp)<=%(end)s and date(o.timestamp)>=%(start)s ...',
               con=db_connection, params={"start":start, "end":end})

CURDATE

使用函数CURDATE可以参数化查询。例如，如果您每周一运行查询并希望提取上周（周一至周日）的数据，则可以设置条件：

WHERE DATE(o.timestamp)<=(CURDATE() - INTERVAL 1 DAY) and DATE(o.timestamp)>=(CURDATE() - INTERVAL 8 DAY)

这显然取决于运行查询时，但如果调度程序自动提取，则效果很好。

或者，将它与DAYOFWEEK结合起来，我们可以让它独立于它运行的那一天（再次：考虑上周一到周日））：

WHERE DATE(o.timestamp) >= (CURDATE() - INTERVAL (DAYOFWEEK(CURDATE())+5) DAY) AND DATE(o.timestamp) <= (CURDATE() - INTERVAL (DAYOFWEEK(CURDATE())-1) DAY)

显然，你必须根据自己的需要调整日偏差。

如何使用Python在SQL查询中自动化日期

1 个答案:

的Python

熊猫的参数

CURDATE