/**
* Performs the actual optimization. In this case the optimizer first
* scans the value. If the value if of type 'datetime' and the column
* is not it tries to make the column datetime. If the column is 'datetime'
* and the value 'datetime' it blocks further optimization. If the value
* is NOT 'datetime' then it immediately returns true, thus allowing further
* optimization.
*
* @return boolean $yesNo advance to next optimizer
*/
public function optimize() {
if (!$this->matchesDateTime($this->value)) return true;
$type = $this->writer->scanType($this->value);
$fields = $this->writer->getColumns($this->table);
if (!in_array($this->column,array_keys($fields))) return false;
$typeInField = $this->writer->code($fields[$this->column]);
if ($typeInField!="datetime") {
if ($this->matchesDateTime($this->value)) {
$cnt = (int) $this->adapter->getCell("select count(*) as n from {$this->table} where
{$this->column} regexp '[0-9]{4}-[0-1][0-9]-[0-3][0-9] [0-2][0-9]:[0-5][0-9]:[0-5][0-9]'
OR {$this->column} IS NULL");
$total = (int) $this->adapter->getCell("SELECT count(*) FROM ".$this->writer->noKW($this->table));
if ($total===$cnt) {
$this->adapter->exec("ALTER TABLE ".$this->writer->noKW($this->table)." change ".$this->writer->noKW($this->column)." ".$this->writer->noKW($this->column)." datetime ");
}
return false;
}
return true;
}
else {
return false;
}
}
