Static DB Connection

config.php

<?php

$config['database'] = [
	'dbname' => 'data',
	'dbhost' => 'localhost',
	'dbdriver' => 'mysql',
	'username' => 'root',
	'password' => 'password'
];

db.php

<?php

require 'config.php';

class DB
{
  public static function connect()
  {
    global $config;
    extract($config['database']);
    $options = [
      PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
      PDO::ATTR_EMULATE_PREPARES => false,
      PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    ];
    $pdo = new PDO("{$dbdriver}:host={$dbhost};dbname={$dbname};", $username, $password, $options);
    return $pdo;
  }

  /**
	 *
	 * @param string  $table
	 * @param string  $cols  (optional)
	 * @param string  $opts  (optional)
	 * @return unknown
	 */
	public static function select(string $table, string $cols = "*", string $opts = "") {
		$stmt = self::connect()->prepare("SELECT {$cols} FROM {$table} {$opts}");
		$stmt->execute();
		return $stmt;
	}


	/**
	 *
	 * @param string  $table
	 * @param string  $cols     (optional)
	 * @param array   $where    (optional)
	 * @param string  $optional (optional)
	 * @return unknown
	 */
	public static function select_where(string $table, string $cols = "*", array $where = [], string $optional = '') {

		$whereCommand = "";

		foreach ($where as $key => $value) {
			$whereCommand .= $key . " = " . "? AND ";
		}

		$whereCommand = rtrim($whereCommand, 'AND ');

		$sql = "SELECT {$cols} FROM $table WHERE {$whereCommand} {$optional}";
		$stmt = self::connect()->prepare($sql);
		$stmt->execute(array_values($where));

		return $stmt;
	}


	/**
	 *
	 * @param string  $table
	 * @param array   $cols
	 * @return unknown
	 */
	public static function insert(string $table, array $cols) {
		$cols_string = implode(", ", array_keys($cols));
		$value_string = implode(", ", array_fill(0, count(array_keys($cols)), '?'));
		$sql = "INSERT INTO $table ({$cols_string}) VALUES ({$value_string});";

		$stmt = self::connect()->prepare($sql);
		try {
			$stmt->execute(array_values($cols));
		} catch (Exception $e) {
			return $e;
		}


	}


	/**
	 *
	 * @param string  $table
	 * @param array   $data  (optional)
	 * @return unknown
	 */
	public static function batch_insert(string $table, array $data = []) {
		//Will contain SQL snippets.
		$rowsSQL = array();

		//Will contain the values that we need to bind.
		$toBind = array();

		//Get a list of column names to use in the SQL statement.
		$columnNames = array_keys($data[0]);

		//Loop through our $data array.
		foreach ($data as $arrayIndex => $row) {
			$params = array();
			foreach ($row as $columnName => $columnValue) {
				$param = ":" . $columnName . $arrayIndex;
				$params[] = $param;
				$toBind[$param] = $columnValue;
			}
			$rowsSQL[] = "(" . implode(", ", $params) . ")";
		}

		//Construct our SQL statement
		$sql = "INSERT INTO `$table` (" . implode(", ", $columnNames) . ") VALUES " . implode(", ", $rowsSQL);

		//Prepare our PDO statement.
		$stmt = self::connect()->prepare($sql);

		//Bind our values.
		foreach ($toBind as $param => $val) {
			$stmt->bindValue($param, $val);
		}

		//Execute our statement (i.e. insert the data).
		return $stmt->execute();
	}


	/**
	 *
	 * @param string  $table
	 * @param array   $colname (optional)
	 * @param array   $data    (optional)
	 * @return unknown
	 */
	public static function update(string $table, array $colname = [], array $data = []) {
		$fieldname = implode(',', array_keys($colname));

		$sqlCommand = "";
		foreach ($data as $key => $value) {
			$sqlCommand .= $key . '=' . '?, ';
		}

		$sqlCommand = rtrim($sqlCommand, ', ');

		$sql = "UPDATE {$table} SET {$sqlCommand} WHERE {$fieldname} = ?";

		$stmt = self::connect()->prepare($sql);
		$params = array_merge(array_values($data), array_values($colname));
		return $stmt->execute($params);
	}


	/**
	 *
	 * @param string  $table
	 * @param array   $colname (optional)
	 * @return unknown
	 */
	public static function delete(string $table, array $colname = []) {
		$fieldname = implode(',', array_keys($colname));
		$sql = "DELETE FROM {$table} WHERE {$fieldname} = ?";
		$stmt = self::connect()->prepare($sql);
		return $stmt->execute(array_values($colname));
	}


	/**
	 * batch_update
	 *
	 *
	 * @param string  $table
	 * @param array   $data    (optional)
	 * @param array   $colname (optional)
	 * @return void
	 */
	public function batch_update(string $table, array $data = [], array $colname = []) {
		if ($this->delete($table, $colname)) {
			//Will contain SQL snippets.
			$rowsSQL = array();

			//Will contain the values that we need to bind.
			$toBind = array();

			//Get a list of column names to use in the SQL statement.
			$columnNames = array_keys($data[0]);

			//Loop through our $data array.
			foreach ($data as $arrayIndex => $row) {
				$params = array();
				foreach ($row as $columnName => $columnValue) {
					$param = ":" . $columnName . $arrayIndex;
					$params[] = $param;
					$toBind[$param] = $columnValue;
				}
				$rowsSQL[] = "(" . implode(", ", $params) . ")";
			}

			//Construct our SQL statement
			$sql = "INSERT INTO `$table` (" . implode(", ", $columnNames) . ") VALUES " . implode(", ", $rowsSQL);


			//Prepare our PDO statement.
			$pdoStatement = self::connect()->prepare($sql);

			//Bind our values.
			foreach ($toBind as $param => $val) {
				$pdoStatement->bindValue($param, $val);
			}

			//Execute our statement (i.e. insert the data).
			return $pdoStatement->execute();
		}
		return false;
	}
}

DB::update('posts', ['id' => 2], ['title' => 'Updated title 2']);