Re: [sqlite] Questions about binding

[James Berry]

On Dec 24, 2004, at 9:56 AM, Dennis Cote wrote:
James Berry wrote:
I think I was most confused by was the use of the word "index" in the
documentation where associated with the bind calls. Index is a
misnomer. It should really be something like "parameter number" as
I've used it above, since index to me implies the index of the
parameter reference within the SQL.
Index was the correct term when it was first used, since SQLite only 
supported positional parameters at that time. The parameter number was 
the index of the parameter in the SQL statement.

Things have gotten more complicated since then. Now, the term index 
really refers to the internal array of parameter values that is 
maintained for each statement.

I don't think it means much to talk about the "parameter number" of a 
named parameter. They should be refered to by their name. To bind a 
value to a named parameter you need to ask SQLite for the index number 
to use for that variable when you make the bind call.
I agree that index makes a certain amount of sense if/once you 
understand the internal implementation. But unless you're looking at 
the code, there's nothing very "indexy" about it, particularly if you 
mix parameter types, or use numbered parameters indiscriminately. Not 
that I would suggest someone do so. And also that indexes in C start at 
0, not 1.

So I came up with the term "parameter number" because it refers to a 
more generic mapping of parameter <==> number. Let's face it: 
parameters are referred to by number through the bind interface, not by 
index. And the mapping of parameter to number is complex. The fact that 
it's called an index is just the implementation leaking through into 
the interface.

Anyway, call it what you want, we just need to be clear that it's not 
an index as one would normally think if it. It's a number predictively 
assigned to the parameter...a parameter number ;)

James
For numbered parameters, the parameter's number is the index by design 
(but it could have been different).

For positional parameters, you still need to count the parameters in 
the SQL statement to determine its index.

I think index is still the best term, it is just that you need to be 
clear that it is an index into the array of bound values, not into the 
text of the SQL statement.

Dennis Cote