Re: Strings: double versus single quotes

[DL Neil via Python-list]

On 24/05/20 5:43 PM, Frank Millman wrote:

On 2020-05-23 9:45 PM, DL Neil via Python-list wrote:


My habit with SQL queries is to separate them from other code, cf the 
usual illustration of having them 'buried' within the code, 
immediately before, or even part of, the query call.




I like that idea, as I find that I am embedding more and more SQL in my 
code.


How do you handle parameters? Do you leave placeholders ('?' or '%s') in 
the query, and leave it to the 'importer' of the query to figure out 
what is required?



Yes. Most "connector" software includes a feature which auto-magically 
escapes all variable-data - a valuable safety feature!


I've been experimenting by going further and providing app.devs with 
functions/methods, a mini-API if you will. Given that many?most don't 
like having to deal with SQL, the extra 'insulation' boosts my personal 
popularity...

(and I need as much of that as I can get!)
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Re: Strings: double versus single quotes

[Frank Millman]

On 2020-05-24 9:58 AM, DL Neil via Python-list wrote:

On 24/05/20 5:43 PM, Frank Millman wrote:

On 2020-05-23 9:45 PM, DL Neil via Python-list wrote:


My habit with SQL queries is to separate them from other code, cf the 
usual illustration of having them 'buried' within the code, 
immediately before, or even part of, the query call.




I like that idea, as I find that I am embedding more and more SQL in 
my code.


How do you handle parameters? Do you leave placeholders ('?' or '%s') 
in the query, and leave it to the 'importer' of the query to figure 
out what is required?



Yes. Most "connector" software includes a feature which auto-magically 
escapes all variable-data - a valuable safety feature!


I've been experimenting by going further and providing app.devs with 
functions/methods, a mini-API if you will. Given that many?most don't 
like having to deal with SQL, the extra 'insulation' boosts my personal 
popularity...

(and I need as much of that as I can get!)


Ok. I will have to give it some thought.

I generate most of my SQL dynamically, constructing the query 
programmatically using the meta-data in my system.


But now I am constructing some more complex queries, which I can't 
generate automatically yet. I am hoping that a pattern emerges which I 
can use to automate them, but for now I am doing it by hand.


There are a number of parameters required, and it will not be obvious at 
first sight what values are required. If I am going to keep the queries 
in a separate module, I think that I will have to provide some sort of 
accompanying documentation with each query explaining what the required 
parameters are.


Thinking aloud, I may set up a separate module for the queries, but make 
each one a 'function', which specifies what data is required. The caller 
calls the function with the data as an argument, and the function uses 
it to build the parameter list and returns the SQL along with the 
parameters. The function can also contain documentation explaining how 
the query works.


As you say, this has the benefit of separating the SQL from the Python 
code, so I will definitely pursue this idea.


Thanks

Frank

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Re: Strings: double versus single quotes

[HÜSEYİN KOÇ]

Çok fazla mail geliyor abonelik iptal için ne yapmam gerekiyor

Android için Outlook'u edinin


From: Python-list  on 
behalf of Frank Millman 
Sent: Sunday, May 24, 2020 11:41:36 AM
To: python-list@python.org 
Subject: Re: Strings: double versus single quotes

On 2020-05-24 9:58 AM, DL Neil via Python-list wrote:
> On 24/05/20 5:43 PM, Frank Millman wrote:
>> On 2020-05-23 9:45 PM, DL Neil via Python-list wrote:
>>>
>>> My habit with SQL queries is to separate them from other code, cf the
>>> usual illustration of having them 'buried' within the code,
>>> immediately before, or even part of, the query call.
>>>
>>
>> I like that idea, as I find that I am embedding more and more SQL in
>> my code.
>>
>> How do you handle parameters? Do you leave placeholders ('?' or '%s')
>> in the query, and leave it to the 'importer' of the query to figure
>> out what is required?
>
>
> Yes. Most "connector" software includes a feature which auto-magically
> escapes all variable-data - a valuable safety feature!
>
> I've been experimenting by going further and providing app.devs with
> functions/methods, a mini-API if you will. Given that many?most don't
> like having to deal with SQL, the extra 'insulation' boosts my personal
> popularity...
> (and I need as much of that as I can get!)

Ok. I will have to give it some thought.

I generate most of my SQL dynamically, constructing the query
programmatically using the meta-data in my system.

But now I am constructing some more complex queries, which I can't
generate automatically yet. I am hoping that a pattern emerges which I
can use to automate them, but for now I am doing it by hand.

There are a number of parameters required, and it will not be obvious at
first sight what values are required. If I am going to keep the queries
in a separate module, I think that I will have to provide some sort of
accompanying documentation with each query explaining what the required
parameters are.

Thinking aloud, I may set up a separate module for the queries, but make
each one a 'function', which specifies what data is required. The caller
calls the function with the data as an argument, and the function uses
it to build the parameter list and returns the SQL along with the
parameters. The function can also contain documentation explaining how
the query works.

As you say, this has the benefit of separating the SQL from the Python
code, so I will definitely pursue this idea.

Thanks

Frank

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Re: Strings: double versus single quotes

[DL Neil via Python-list]

On 24/05/20 8:41 PM, Frank Millman wrote:

On 2020-05-24 9:58 AM, DL Neil via Python-list wrote:

On 24/05/20 5:43 PM, Frank Millman wrote:

On 2020-05-23 9:45 PM, DL Neil via Python-list wrote:


My habit with SQL queries is to separate them from other code, cf 
the usual illustration of having them 'buried' within the code, 
immediately before, or even part of, the query call.




I like that idea, as I find that I am embedding more and more SQL in 
my code.


How do you handle parameters? Do you leave placeholders ('?' or '%s') 
in the query, and leave it to the 'importer' of the query to figure 
out what is required?



Yes. Most "connector" software includes a feature which auto-magically 
escapes all variable-data - a valuable safety feature!


I've been experimenting by going further and providing app.devs with 
functions/methods, a mini-API if you will. Given that many?most don't 
like having to deal with SQL, the extra 'insulation' boosts my 
personal popularity...

(and I need as much of that as I can get!)


Ok. I will have to give it some thought.

I generate most of my SQL dynamically, constructing the query 
programmatically using the meta-data in my system.


But now I am constructing some more complex queries, which I can't 
generate automatically yet. I am hoping that a pattern emerges which I 
can use to automate them, but for now I am doing it by hand.


There are a number of parameters required, and it will not be obvious at 
first sight what values are required. If I am going to keep the queries 
in a separate module, I think that I will have to provide some sort of 
accompanying documentation with each query explaining what the required 
parameters are.


Thinking aloud, I may set up a separate module for the queries, but make 
each one a 'function', which specifies what data is required. The caller 
calls the function with the data as an argument, and the function uses 
it to build the parameter list and returns the SQL along with the 
parameters. The function can also contain documentation explaining how 
the query works.


As you say, this has the benefit of separating the SQL from the Python 
code, so I will definitely pursue this idea.



We have been talking (slightly OT for thread - apologies) about the 
narrow sub-objectives of transferring data between a Python application 
and an RDBMS. May I advise consideration of the wider specification?


For example, one may find it helpful to use a library/abstraction such 
as SQLAlchemy. Such facilitates transaction data being taken directly 
from/returned to a Python class! Whereas this discussion (above) only 
returns raw data-items, thus necessitating the application programmers 
coding an appropriate 'getter' to provide data to the RDBMS 
interface-functions, and/or a 'setter' to absorb query-results into the 
application's data-class(es)!


Of course, there are plenty of applications where one might eschew such 
advantages, eg a simple interface, and at the other end of the scale: if 
the data were to be formatted into a pandas data-frame.


Horses for courses!
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stderr writting before stdout

[Souvik Dutta]

Hi,
Is there any precedence or priority order by which sys.stderr.write() and
sys.stdout.write() works. Because when running the below code...

import sys
sys.stdout.write("Writting")
sys.stderr.write("No errors \n")

No errors is written (displayed) first and writting is written later. Why
does this happen?
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Re: stderr writting before stdout

[Dylan Evans]

Hi,
This data is being line buffered, so either a newline or flush is required
to get it to actually write to the terminal / file.

On Sun, May 24, 2020 at 2:34 PM Souvik Dutta 
wrote:

> Also this code maintains order i.e. writting is displayed before no errors.
> Why is that?
>
> import sys
> sys.stdout.write("Writting \n")
> sys.stderr.write("No errors \n")
>
> On Sun, 24 May, 2020, 9:57 am Souvik Dutta, 
> wrote:
>
> > Hi,
> > Is there any precedence or priority order by which sys.stderr.write() and
> > sys.stdout.write() works. Because when running the below code...
> >
> > import sys
> > sys.stdout.write("Writting")
> > sys.stderr.write("No errors \n")
> >
> > No errors is written (displayed) first and writting is written later. Why
> > does this happen?
> >
> >
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>
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