Abstract vendor-specific implementations such as Concat

[VexedPanda]

There are a number of SQL functions that do not have standard-based usage patters among the large server vendors. We should still allow the use of these within QQ.

An example is concat, where each DB supports it, but each has different syntax to accomplish it.

[alex94040]

To get this started, we should create a list of these functions. I also don't think that this should be a part of the 1.1 release - let's push it out.

[VexedPanda]

Case sensitive like statements are also different between vendors (ie: oracle)

[olegabr]

I'm solving this problem for myself in this way:

	//QQuery.class.php:

	// Used to wrap databse specific strings like "now()::time + interval '60 seconds'" for PostgreSQL
	// to prevent hiding of ' with slashes
	class QDbSpecific {
		protected $strDbSpecificValue;
		public function __construct($strDbSpecificValue) {
			$this->strDbSpecificValue = $strDbSpecificValue;
		}
		public function __toString() {
			return $this->strDbSpecificValue;
		}
	}
	class QQ {
		/////////////////////////
		// QQCondition Factories
		/////////////////////////

		static public function DbSpecific() {
			return new QDbSpecific(implode(func_get_args()));
		}

		// ... //
	}

Usage:

	$condTime = QQ::LessOrEqual(QQN::Request()->TimeBegin,
		QQ::DbSpecific("(now()::time + interval '" . $intSeconds . " seconds')"));

It allows to use any DB-specific constructs in the "value" part of QQ-conditions.