RE: [sqlite] Query generation

[Fred Williams]

Pusedo code:

set s.sql = 'select a from mytable where (b=0)';
if got.more then 
  set s.sql = s.sql + ' and ' + s.userinput;
...
set s.sql = s.sql + ';';

> -Original Message-
> From: Lloyd [mailto:[EMAIL PROTECTED]
> Sent: Thursday, December 07, 2006 2:46 AM
> To: sqlite-users@sqlite.org
> Subject: [sqlite] Query generation
> 
> 
> Hi,
>  I am generating queries dynamically from my program based on 
> the input.
> The primary part of the query is always
> 
> select a from mytable where (b=0) and
> 
> based on the user input I add more where clauses to my query like
> 
> select a from mytable where (b=0) and (x=10)
> 
> but in one case there in no where clause to add, so my final query
> become
> 
> select a from mytable where (b=0) and
> 
> and this is a syntax error.
> 
> Is there any option to add a null clause after the 'and' ?
> 
> Thanks,
>   Lloyd
> 
> 
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Re: [sqlite] Query generation

[Darren Duncan]

At 2:15 PM +0530 12/7/06, Lloyd wrote:

Hi,
 I am generating queries dynamically from my program based on the input.
The primary part of the query is always
select a from mytable where (b=0) and
based on the user input I add more where clauses to my query like
select a from mytable where (b=0) and (x=10)
but in one case there in no where clause to add, so my final query
become
select a from mytable where (b=0) and
and this is a syntax error.
Is there any option to add a null clause after the 'and' ?
Thanks,
  Lloyd


A better solution is to use leading 'and' rather than trailing 'and', 
so you should start off with:


  select a from mytable where (b=0)

... which is already valid syntax, and only add a bunch of "and 
" when you actually have the "".


-- Darren Duncan

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Re: [sqlite] Query generation

[Lloyd]

Thanks, 0=0 works well enough for me. (This hint is what I wanted)

Thanks again,
  Lloyd

On Wed, 2006-12-06 at 10:00 +0100, Mario Frasca wrote:
> Lloyd wrote:
> 
> >select a from mytable where (b=0) and
> >
> >and this is a syntax error.
> >  
> >
> you're not saying which language you're using.
> 
> in Python a common solution looks like this:
> clauses = []
> # add strings to the clauses list, like
> clauses.append('(b=0)')
> # join the parts using appropriate glue
> where = ' AND '.join(clauses)
> 
> sometimes I do need something like what you call "an empty clause"...
> some engines accept 'TRUE', others don't know that literal.
> I find this quite convenient:
> '0=0'
> 
> hth...
> 
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Re: [sqlite] Query generation

[Mario Frasca]

Lloyd wrote:


select a from mytable where (b=0) and

and this is a syntax error.
 


you're not saying which language you're using.

in Python a common solution looks like this:
clauses = []
# add strings to the clauses list, like
clauses.append('(b=0)')
# join the parts using appropriate glue
where = ' AND '.join(clauses)

sometimes I do need something like what you call "an empty clause"...
some engines accept 'TRUE', others don't know that literal.
I find this quite convenient:
'0=0'

hth...

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