class Insert

class Insert extends Query implements \Countable {
    use InsertTrait;
    
    /**
     * A SelectQuery object to fetch the rows that should be inserted.
     *
     * @var \Drupal\Core\Database\Query\SelectInterface
     */
    protected $fromQuery;
    
    /**
     * Constructs an Insert object.
     *
     * @param \Drupal\Core\Database\Connection $connection
     *   A Connection object.
     * @param string $table
     *   Name of the table to associate with this query.
     * @param array $options
     *   Array of database options.
     */
    public function __construct($connection, $table, array $options = []) {
        parent::__construct($connection, $options);
        $this->table = $table;
    }
    
    /**
     * Sets the fromQuery on this InsertQuery object.
     *
     * @param \Drupal\Core\Database\Query\SelectInterface $query
     *   The query to fetch the rows that should be inserted.
     *
     * @return $this
     *   The called object.
     */
    public function from(SelectInterface $query) {
        $this->fromQuery = $query;
        return $this;
    }
    
    /**
     * Executes the insert query.
     *
     * @return int|null|string
     *   The last insert ID of the query, if one exists. If the query was given
     *   multiple sets of values to insert, the return value is undefined. If no
     *   fields are specified, this method will do nothing and return NULL. That
     *   That makes it safe to use in multi-insert loops.
     */
    public function execute() {
        // If validation fails, simply return NULL. Note that validation routines
        // in preExecute() may throw exceptions instead.
        if (!$this->preExecute()) {
            return NULL;
        }
        // If we're selecting from a SelectQuery, finish building the query and
        // pass it back, as any remaining options are irrelevant.
        if (!empty($this->fromQuery)) {
            $sql = (string) $this;
            // The SelectQuery may contain arguments, load and pass them through.
            return $this->connection
                ->query($sql, $this->fromQuery
                ->getArguments(), $this->queryOptions);
        }
        $last_insert_id = 0;
        $stmt = $this->connection
            ->prepareStatement((string) $this, $this->queryOptions);
        try {
            // Per https://en.wikipedia.org/wiki/Insert_%28SQL%29#Multirow_inserts,
            // not all databases implement SQL-92's standard syntax for multi-row
            // inserts. Therefore, in the degenerate case, execute a separate query
            // for each row, all within a single transaction for atomicity and
            // performance.
            $transaction = $this->connection
                ->startTransaction();
            foreach ($this->insertValues as $insert_values) {
                $stmt->execute($insert_values, $this->queryOptions);
                $last_insert_id = $this->connection
                    ->lastInsertId();
            }
        } catch (\Exception $e) {
            if (isset($transaction)) {
                // One of the INSERTs failed, rollback the whole batch.
                $transaction->rollBack();
            }
            // Rethrow the exception for the calling code.
            throw $e;
        }
        // Re-initialize the values array so that we can re-use this query.
        $this->insertValues = [];
        // Transaction commits here where $transaction looses scope.
        return $last_insert_id;
    }
    
    /**
     * Implements PHP magic __toString method to convert the query to a string.
     *
     * @return string
     *   The prepared statement.
     */
    public function __toString() {
        // Create a sanitized comment string to prepend to the query.
        $comments = $this->connection
            ->makeComment($this->comments);
        // Default fields are always placed first for consistency.
        $insert_fields = array_merge($this->defaultFields, $this->insertFields);
        if (!empty($this->fromQuery)) {
            return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') ' . $this->fromQuery;
        }
        // For simplicity, we will use the $placeholders array to inject
        // default keywords even though they are not, strictly speaking,
        // placeholders for prepared statements.
        $placeholders = [];
        $placeholders = array_pad($placeholders, count($this->defaultFields), 'default');
        $placeholders = array_pad($placeholders, count($this->insertFields), '?');
        return $comments . 'INSERT INTO {' . $this->table . '} (' . implode(', ', $insert_fields) . ') VALUES (' . implode(', ', $placeholders) . ')';
    }
    
    /**
     * Preprocesses and validates the query.
     *
     * @return bool
     *   TRUE if the validation was successful, FALSE if not.
     *
     * @throws \Drupal\Core\Database\Query\FieldsOverlapException
     * @throws \Drupal\Core\Database\Query\NoFieldsException
     */
    protected function preExecute() {
        // Confirm that the user did not try to specify an identical
        // field and default field.
        if (array_intersect($this->insertFields, $this->defaultFields)) {
            throw new FieldsOverlapException('You may not specify the same field to have a value and a schema-default value.');
        }
        if (!empty($this->fromQuery)) {
            // We have to assume that the used aliases match the insert fields.
            // Regular fields are added to the query before expressions, maintain the
            // same order for the insert fields.
            // This behavior can be overridden by calling fields() manually as only the
            // first call to fields() does have an effect.
            $this->fields(array_merge(array_keys($this->fromQuery
                ->getFields()), array_keys($this->fromQuery
                ->getExpressions())));
        }
        else {
            // Don't execute query without fields.
            if (count($this->insertFields) + count($this->defaultFields) == 0) {
                throw new NoFieldsException('There are no fields available to insert with.');
            }
        }
        // If no values have been added, silently ignore this query. This can happen
        // if values are added conditionally, so we don't want to throw an
        // exception.
        if (!isset($this->insertValues[0]) && count($this->insertFields) > 0 && empty($this->fromQuery)) {
            return FALSE;
        }
        return TRUE;
    }

}