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PDO::PARAM_DOUBLE

php.internals

Adam Baratz

9 years ago
If you want to bind a double to a statement, the accepted approach is to bind as a string: http://stackoverflow.com/questions/2718628/pdoparam-for-type-decimal However, this means that prepared statements see these values as strings. This can cause issues, for example: http://stackoverflow.com/questions/38105900/sqlite-having-comparison-error pdo_mysql will actually watch for doubles, but this code will never be reached since all doubles are cast to strings: https://github.com/php/php-src/blob/3f25c4228a8f505a000c1ea5751062606247349a/ext/pdo_mysql/mysql_statement.c#L563 Is there a reason PDO::PARAM_DOUBLE doesn't exist? Thanks, Adam

Matteo Beccati

9 years ago
Hi, On 07/12/2016 22:39, Adam Baratz wrote:
> If you want to bind a double to a statement, the accepted approach is to > bind as a string: > http://stackoverflow.com/questions/2718628/pdoparam-for-type-decimal
For decimal, double wouldn't be the correct type anyway, as it could cause loss of precision.
> Is there a reason PDO::PARAM_DOUBLE doesn't exist?
I don't know if there's am historical reason. I think it should be there, but to be honest, I'm not sure it's worth the effort at this point. Cheers
-- Matteo Beccati Development & Consulting - http://www.beccati.com/

Adam Baratz

9 years ago
> > For decimal, double wouldn't be the correct type anyway, as it could > cause loss of precision. >
Sure, agree the name is imprecise. "Double" is mainly relevant to zvals.
> Is there a reason PDO::PARAM_DOUBLE doesn't exist? > > I don't know if there's am historical reason. I think it should be > there, but to be honest, I'm not sure it's worth the effort at this point.
Say more on why you don't think there'd be a payoff? I'd think that it would be worth taking the (I'm guessing) max. 3 days involved to add missing functionality to a widely-used extension.

Matteo Beccati

9 years ago
Hi Adam, On 07/12/2016 23:37, Adam Baratz wrote:
> For decimal, double wouldn't be the correct type anyway, as it could > cause loss of precision. > > > Sure, agree the name is imprecise. "Double" is mainly relevant to zvals.
It's not about naming. Double is relevant both to PHP and SQL and is a floating point type. On the other hand, decimal/numeric fields should be represented as strings as they are fixed point/precision, which is something we don't have in stock php. In fact bcmath uses strings too.
> > Is there a reason PDO::PARAM_DOUBLE doesn't exist? > > I don't know if there's am historical reason. I think it should be > there, but to be honest, I'm not sure it's worth the effort at this > point. > > > Say more on why you don't think there'd be a payoff? I'd think that it > would be worth taking the (I'm guessing) max. 3 days involved to add > missing functionality to a widely-used extension.
I think it would be the biggest PDO API change to date and we should be very careful. Lots of #ifdefs for pecl pdo_* developers to add, if they want to keep their extensions backwards compatible. My biggest worry is its potential misuse for decimal fields. I know this isn't reason enough for denying an improvement, but there are already too many people mistakenly using double for currency data and monetary calculations... That said, I think this more than anything else requires a proper RFC and discussion. Cheers
-- Matteo Beccati Development & Consulting - http://www.beccati.com/

Andrew Faulds

9 years ago
Hi, Matteo Beccati wrote:
> Hi Adam, > > On 07/12/2016 23:37, Adam Baratz wrote: >> For decimal, double wouldn't be the correct type anyway, as it could >> cause loss of precision. >> >> >> Sure, agree the name is imprecise. "Double" is mainly relevant to zvals. > > It's not about naming. Double is relevant both to PHP and SQL and is a > floating point type. On the other hand, decimal/numeric fields should be > represented as strings as they are fixed point/precision, which is > something we don't have in stock php. In fact bcmath uses strings too.
On the subject of naming, if we were to add this, I would think the name should be PDO::PARAM_FLOAT instead, as that's the more common name for the PHP float type now. It's IS_DOUBLE internally, but that is mostly an implementation detail, like IS_LONG. Thanks.
-- Andrea Faulds https://ajf.me/