private function gatherAlterColumnSQL(Identifier $table, ColumnDiff $columnDiff, array &$sql, array &$queryParts)
    {
        $alterColumnClauses = $this->getAlterColumnClausesSQL($columnDiff);

        if (empty($alterColumnClauses)) {
            return;
        }

        // If we have a single column alteration, we can append the clause to the main query.
        if (count($alterColumnClauses) === 1) {
            $queryParts[] = current($alterColumnClauses);

            return;
        }

        // We have multiple alterations for the same column,
        // so we need to trigger a complete ALTER TABLE statement
        // for each ALTER COLUMN clause.
        foreach ($alterColumnClauses as $alterColumnClause) {
            $sql[] = 'ALTER TABLE ' . $table->getQuotedName($this) . ' ' . $alterColumnClause;
        }
    }