I understand the problem, but I want my library to be able to detect the
problem programatically.
Currently if a user mixes index-based and key-based placeholders, the only
thing a library using SQLite can do us run the query with unbound
placeholders set to null (the SQLite default).
Id like the ability to instead throw an error in this case.
I think SQLite internally knows how many placeholders are in the query at
parse time.
My question is how can I get the data via the API, or if it would be
considered to add a function to get this data?
On Mon, Jul 22, 2019 at 12:29 PM Keith Medcalf <kmedc...@dessus.com> wrote:
>
> On Monday, 22 July, 2019 04:34, Enzo <contact.enz...@gmail.com> wrote:
>
> >It is not the same information.
>
> >I want to be able to determine "has the user bound all placeholder
> >values with data?".
>
> >The user provides this as input:
>
> >query="SELECT ?, ?10"
> >data={"0": "data-a", "10": "data-b"}
>
> >Note: This IS valid, as they have provided all data for placeholders.
>
> >Using the APIs you mentioned:
>
> >count=10
> >name(10) = "?10"
>
> >So according to the API, the indexes [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> >are placeholders in the query.
>
> >As you can see, only indexes [1, 10] are valid placeholders in the
> >query.
>
> >So, as far as I can tell, it is not possible to get this from the
> >API:
>
> >query="SELECT ?, ?10"
> >valid_placeholder_indexes=[1, 10]
>
> >It is only possible to get this:
>
> >query="SELECT ?, ?10"
> >maybe_placeholder_indexes=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>
> The fundamental issue is that you are confusing POSITIONAL parameters with
> NAMED parameters. ?nnn where nnn is numeric describe POSITIONAL
> parameters, so in the query SELECT ?, ?10 you are using positional
> parameter 1 and positional parameter 10. That implies that there are 10
> positional parameters. The fact that you are only using those positional
> parameters sparsely (only using positional parameter 1 and positional
> parameter 10) does not mean that you are using two parameters, it means
> that you are using 10, but only referencing 2 of them.
>
> Said another way, you are declaring a function that looks like this:
>
> int stmt(a, b, c, d, e, f, g, h, i, j)
> return a + j
>
> and expecting to be able to call it as
>
> z = stmt(1, 6)
>
> expecting some magic to know that the second parameter is really parameter
> 10.
>
> https://www.sqlite.org/lang_expr.html#varparam
>
> There may be many positional parameters (like 999 in the default build)
> and sqlite3_bind_parameter_count returns the "index" of the greatest
> parameter number used in the statement. Having created 10 parameters
> sqlite has absolutely no clue that you happen to be using only parameter 1
> and parameter 10. If you only needed 2 parameters you should have only
> created 2, not 10. That is what NAMED parameters are for.
>
> If you change from using positional (?) parameters to using named (:) or
> (@) what happens?
>
> select :1, :10; should only create 2 parameters named :1 and :10 ...
>
> --
> The fact that there's a Highway to Hell but only a Stairway to Heaven says
> a lot about anticipated traffic volume.
>
>
>
>
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