Tukar lajur dalam PostgreSQL

Menukar lajur jadual SQL adalah sebahagian daripada repertoar standard dengan MySQL - ini belum (belum) disokong dengan PostgreSQL. Walaupun wiki rasmi mencurahkan artikelnya sendiri untuk masalah itu, ia tidak menunjukkan penyelesaian praktikal yang juga menyokong pandangan, indeks dan pencetus. Kelas berikut melakukan tugas ini (untuk MySQL dan PostgreSQL) sama ada pada baris arahan - atau sebagai alternatif langsung di Laravel 5.


<?php
namespace App\Helpers;
class ColumnChanger
{

	public static $quotes;

	public static $path;

	public static function swap($table, $col1, $col2)
	{

		// initialize

		self::$quotes = self::getQuotes();
		self::$path = self::getPath();

		// export

		$content = self::exportDB();

		// swap

		$content = self::swapNow($table, $col1, $col2, $content);

		// import

		self::importDB($content);
	}

	public static function getQuotes()
	{
		if (getenv("DB_CONNECTION") == "pgsql")
		{
			return "";
		}

		if (getenv("DB_CONNECTION") == "mysql")
		{
			return "`";
		}
	}

	public static function getPath()
	{
		if (getenv("DB_CONNECTION") == "pgsql")
		{
			$sql = new \PDO('pgsql:host=' . getenv('DB_HOST') . ';port=' . getenv('DB_PORT') . ';dbname=' . getenv('DB_DATABASE') , getenv('DB_USERNAME') , getenv('DB_PASSWORD'));
			$stmt = $sql->prepare("SHOW data_directory");
			$stmt->execute();
			$path = str_replace("data", "bin", $stmt->fetchObject()->data_directory) . "/";
		}

		if (getenv("DB_CONNECTION") == "mysql")
		{
			$sql = new \PDO('mysql:host=' . getenv('DB_HOST') . ';port=' . getenv('DB_PORT') . ';dbname=' . getenv('DB_DATABASE') , getenv('DB_USERNAME') , getenv('DB_PASSWORD'));
			$stmt = $sql->prepare("SHOW VARIABLES LIKE 'basedir'");
			$stmt->execute();
			$path = $stmt->fetchObject()->Value . "bin/";
		}

		return $path;
	}

	public static function exportDB()
	{
		if (getenv("DB_CONNECTION") == "pgsql")
		{
			putenv("PGPASSWORD=" . getenv('DB_PASSWORD'));
			exec('"' . self::$path . 'pg_dump" --clean --inserts -h ' . getenv('DB_HOST') . ' -p ' . getenv('DB_PORT') . ' -U ' . getenv('DB_USERNAME') . ' ' . getenv('DB_DATABASE') . ' > db.sql');
		}

		if (getenv("DB_CONNECTION") == "mysql")
		{
			exec('"' . self::$path . 'mysqldump" -h ' . getenv('DB_HOST') . ' --port ' . getenv('DB_PORT') . ' -u ' . getenv('DB_USERNAME') . ' -p"' . getenv('DB_PASSWORD') . '" ' . getenv('DB_DATABASE') . ' > db.sql');
		}

		return file_get_contents("db.sql");
	}

	public static function importDB($content)
	{
		file_put_contents("db.sql", $content);
		if (getenv("DB_CONNECTION") == "pgsql")
		{
			putenv("PGPASSWORD=" . getenv('DB_PASSWORD'));
			exec('"' . self::$path . 'psql" -h ' . getenv('DB_HOST') . ' -p ' . getenv('DB_PORT') . ' -U ' . getenv('DB_USERNAME') . ' -d ' . getenv('DB_DATABASE') . ' -1 -f db.sql');
		}

		if (getenv("DB_CONNECTION") == "mysql")
		{
			exec('"' . self::$path . 'mysql" -h ' . getenv('DB_HOST') . ' --port ' . getenv('DB_PORT') . ' -u ' . getenv('DB_USERNAME') . ' -p"' . getenv('DB_PASSWORD') . '" ' . getenv('DB_DATABASE') . ' --default-character-set=utf8 < db.sql');
		}

		unlink("db.sql");
	}

	public static function getPositions($haystack, $needle)
	{
		$positions = [];
		$lastPos = 0;
		while (($lastPos = strpos($haystack, $needle, $lastPos)) !== false)
		{
			$positions[] = $lastPos;
			$lastPos = $lastPos + strlen($needle);
		}

		return $positions;
	}

	public static function getEnd($content, $begin)
	{
		$end = $begin;
		$outside = true;
		while ($outside !== true || $content[$end] != ";")
		{
			if ($content[$end] == "'")
			{
				if ($end === 0 || $content[$end - 1] != "\")
				{
					$outside = !$outside;
				}
			}

			$end++;
		}

		return ++$end;
	}

	public static function splitString($string)
	{
		return preg_split('/(?<!^)(?!$)/u', $string);
	}

	public static function getColumns($query)
	{
		$i = 0;
		$outside = true;
		$query = self::splitString($query);
		foreach($query as $i => $char)
		{
			if ($query[$i] == "'")
			{
				if ($i === 0 || $query[$i - 1] != "\")
				{
					$outside = !$outside;
				}
			}

			if ($outside === true && $query[$i] == ",")
			{
				$query[$i] = "♥";
			}

			$i++;
		}

		$query = implode("", $query);
		$cols = explode("♥", $query);
		return $cols;
	}

	public static function swapNow($table, $col1, $col2, $content)
	{

		// loop through relevant statements

		foreach(["CREATE TABLE " . self::$quotes . $table . self::$quotes, "INSERT INTO " . self::$quotes . $table . self::$quotes] as $skey => $statement)
		{
			$positions = self::getPositions($content, $statement);
			foreach($positions as $position)
			{
				$begin = $position;
				$end = self::getEnd($content, $begin);
				$query_all = substr($content, $begin, $end - $begin);
				$query_inside = substr($query_all, strpos($query_all, "(") + 1, strrpos($query_all, ")") - strpos($query_all, "(") - 1);

				// get columns

				$cols = self::getColumns($query_inside);

				// get relevant column indexes

				if ($skey == 0)
				{
					$col1pos = 0;
					$col2pos = 0;
					foreach($cols as $pos => $col)
					{
						$col = trim($col);
						if (strpos($col, self::$quotes . $col1 . self::$quotes) === 0)
						{
							$col1pos = $pos;
						}

						if (strpos($col, self::$quotes . $col2 . self::$quotes) === 0)
						{
							$col2pos = $pos;
						}
					}
				}

				// swap columns

				$tmp = $cols[$col1pos];
				$cols[$col1pos] = $cols[$col2pos];
				$cols[$col2pos] = $tmp;
				$query_inside_new = implode(",", $cols);

				// insert query into content

				$query_all_new = str_replace($query_inside, $query_inside_new, $query_all);
				$content = str_replace($query_all, $query_all_new, $content);
			}
		}

		return $content;
	}
}

// usage from the command line

if (isset($argv) && is_array($argv))
{
	$args = [];
	foreach($argv as $key => $arg)
	{
		switch ($arg)
		{
		case "-e":
			$args["engine"] = $argv[$key + 1];
			break;

		case "-h":
			$args["hostname"] = $argv[$key + 1];
			break;

		case "-P":
			$args["port"] = $argv[$key + 1];
			break;

		case "-u":
			$args["username"] = $argv[$key + 1];
			break;

		case "-p":
			$args["password"] = $argv[$key + 1];
			break;

		case "-d":
			$args["database"] = $argv[$key + 1];
			break;

		case "-t":
			$args["table"] = $argv[$key + 1];
			break;
		}
	}

	// set default values

	if (!isset($args["hostname"]))
	{
		$args["hostname"] = "127.0.0.1";
	}

	if (!isset($args["port"]) && isset($args["engine"]) && $args["engine"] == "mysql")
	{
		$args["port"] = "3306";
	}

	if (!isset($args["port"]) && isset($args["engine"]) && $args["engine"] == "pgsql")
	{
		$args["port"] = "5432";
	}

	foreach($args as $option => $arg)
	{
		if (!isset($arg))
		{
			die('missing option ' . $option);
		}
	}

	if (count($argv) < 2)
	{
		die('error');
	}

	$args["col1"] = $argv[count($argv) - 2];
	$args["col2"] = $argv[count($argv) - 1];
	putenv("DB_CONNECTION=" . $args["engine"]);
	putenv("DB_HOST=" . $args["hostname"]);
	putenv("DB_PORT=" . $args["port"]);
	putenv("DB_DATABASE=" . $args["database"]);
	putenv("DB_USERNAME=" . $args["username"]);
	putenv("DB_PASSWORD=" . $args["password"]);
	ColumnChanger::swap($args["table"], $args["col1"], $args["col2"]);
	
}

Panggilan pada baris arahan sangat jelas:

php ColumnChanger.php -e pgsql -h 127.0.0.1 -P 5432 -u username -p password -d database -t table col1 col2
php ColumnChanger.php -e mysql -h 127.0.0.1 -P 3306 -u username -p password -d database -t table col1 col2

Integrasi dalam Laravel 5 juga dilakukan dengan cepat dengan hanya menyalin ColumnChanger.php ke dalam folder app / Helpers. Anda kemudian boleh menukar lajur secara langsung dalam migrasi:

<?php
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;

class SwitchColumns extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        App\Helpers\ColumnChanger::swap("users","email","password");
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        App\Helpers\ColumnChanger::swap("users","password","email");
    }
}
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