with-statement

问题 First I'll explain you the situation. I want to transfer data from one table(View_Solidnet_Training) to another(OBJ_Availability). There is one problem: In the view there is a Start- and EndDate! In OBJ_Availability every date has one record. So one line in the view has multi lines in the other table. I must work with CTE. So cursor is no option for me. The middle WITH runs perfect, but when I want to add an extra WITH to check if the ID isn't zero, it must change the variable @Start and @End

问题 This should be pretty easy, not sure why I can't get it to work. I am trying to import a ton of .txt files as part of a larger process like so: path = "C:/Users/A/B/" with open(path + "*full.txt","r") as f: contents =f.read() print(contents) I am just trying to import all .txt files (there are a ton of them) in this folder path, when I do this I get: OSError: [Errno 22] Invalid argument: There are strings in the middle that are different between each file hence the * before the full it lists

问题 Original Code: import sys import os import latexmake import mysql.connector conn = mysql.connector.connect(user='root',password='oilwell',host='localhost',database='sqlpush1') with conn: mycursor = conn.cursor() mycursor=execute("SELECT DATE,oil,gas,oilprice,gasprice,totrev FROM results WHERE DATE BETWEEN '2011-01-01' AND '2027-12-01'") rows = mycursor.fetchall() a.write("\\documentclass{standalone}\\usepackage{booktabs}\n\n\\usepackage{siunitx}\r \n\ \r\n\\begin{document}\r\n\\begin{tabular}

问题 This question is a follow up from following question:With statement and python threading I have been experimenting with python threading api. I have this code which works for what I want to achieve :---->function execution before invoking run on python thread. However to do this, I invariably have to call time.sleep(1) in the run() method to make it proceed to execute().Otherwise the thread exits without function assignment and execution.Is there a better way to achieve this type of waiting?

问题 I have a project that needs to read data, then write in more than 23 CSV files in parallel depending on each line. For example, if the line is about temperature, we should write to temperature.csv, if about humidity, >>to humid.CSV , etc. I tried the following: with open('Results\\GHCN_Daily\\MetLocations.csv','wb+') as locations, \ open('Results\\GHCN_Daily\\Tmax.csv','wb+')as tmax_d, \ open('Results\\GHCN_Daily\\Tmin.csv','wb+')as tmin_d, \ open('Results\\GHCN_Daily\\Snow.csv', 'wb+')as

问题 I need to update some rows in a DB table. How I identify the rows to be updated involved a series of complicated statements, and I managed to boil them down to a series of WITH statements. Now I have the correct data values, I need to update the table. Since I managed to get these values with a WITH statement, I was hoping to use it in the UPDATE/MERGE. A simplified example follows: with data1 ( ID_1 ) as ( Select ID from ID_TABLE where ID > 10 ) , cmedb.data2 ( MIN_ORIGINAL_ID ,OTHER_ID ) as

问题 This question already has answers here : will using list comprehension to read a file automagically call close() (5 answers) Closed 2 years ago . I came across this syntax for reading the lines in a file. with open(...) as f: for line in f: <do something with line> Say I wanted the <do something with line> line to append each line to a list. Is there any way to accomplish this, using the with keyword, in a list comprehension? Or, is there at least some way of doing what I want in a single

问题 My understanding of the WITH statement (CTE) is that it executes once per query. With a query like this: WITH Query1 AS ( ... ) SELECT * FROM SomeTable t1 LEFT JOIN Query1 t2 ON ... If this results in 100 rows, I expect that Query1 was executed only once - not 100 times. If that assumption is correct, the time taken to run the entire query is roughly equal to the time taken to: run Query1 + select from SomeTable + join SomeTable to Query1 . I am in a situation where: Query1 when run alone

问题 Is there a way I can catch exceptions in the __enter__ method of a context manager without wrapping the whole with block inside a try ? class TstContx(object): def __enter__(self): raise Exception("I'd like to catch this exception") def __exit__(self, e_typ, e_val, trcbak): pass with TstContx(): raise Exception("I don't want to catch this exception") pass I know that I can catch the exception within __enter__() itself, but can I access that error from the function that contains the with

问题 Python 3.4 provides this neat tool to temporarily redirect stdout: # From https://docs.python.org/3.4/library/contextlib.html#contextlib.redirect_stdout with redirect_stdout(sys.stderr): help(pow) The code is not super-complicated, but I wouldn't want to write it over and over again, especially since some thought has gone into it to make it re-entrant: class redirect_stdout: def __init__(self, new_target): self._new_target = new_target # We use a list of old targets to make this CM re-entrant