Added JDatabaseQuery function to extract part of timestamp.

[gpongelli]

This function is used to extract part of date from timestamp in a database independent manner.
Added MySQL test of element string conversion.

Usage:
$query->day($query->quoteName('dateColumn'))
for MySQL will return "DAY( dateColumn )"

$query->month($query->quoteName('dateColumn'))
for MySQL will return "MONTH( dateColumn )"

$query->year($query->quoteName('dateColumn'))
for MySQL will return "YEAR( dateColumn )"

$query->hour($query->quoteName('dateColumn'))
for MySQL will return "HOUR( dateColumn )"

$query->minute($query->quoteName('dateColumn'))
for MySQL will return "MINUTE( dateColumn )"

$query->second($query->quoteName('dateColumn'))
for MySQL will return "SECOND( dateColumn )"

[joomla-jenkins]

Unit testing complete. There were 1 failures and 0 errors from 1944 tests and 11088 assertions.
Checkstyle analysis reported 165 warnings and 0 errors.

[joomla-jenkins]

Build triggered by changes to the head.

Unit testing complete. There were 0 failures and 0 errors from 1944 tests and 11091 assertions.
Checkstyle analysis reported 165 warnings and 0 errors.

[chdemko]

Would it be simpler to add these functions (and thus restrict the 'part' value)

public function year($date)
public function month($date)
public function day($date)
public function hour($date)
public function minute($date)
public function second($date)
public function microsecond($date)

?

Allowing to precise the 'part', developers could use some mysql functions that could not exist in other db engines

[gpongelli]

Yes it could be simpler.
I've added only that function because of same word use in each database's documentation, but this proposal is interesting.

Ing. Gabriele Pongelli

[eddieajau]

Are there differences in the way different databases handle the date parts?

[gpongelli]

Yes, an example extracting year from a date between MySQL and PostgreSQL .

Mysql: YEAR(dateColumn)
PostgreSQL: EXTRACT(YEAR FROM dateColumn)

Eng. Gabriele Pongelli

[eddieajau]

Ok, in that case I agree with Christophe. I think it would be better to add the extra methods.

[gpongelli]

I did the changes locally but I haven't pushed them yet, I'll do soon.

Eng. Gabriele Pongelli.

[gpongelli]

Pushed last commits.

Eng. Gabriele Pongelli.

[joomla-jenkins]

Build triggered by changes to the head.

Unit testing complete. There were 0 failures and 0 errors from 1991 tests and 11149 assertions.
Checkstyle analysis reported 165 warnings and 0 errors.

[eddieajau]

Nice job. Merged.