presto-parser/src/main/java/io/prestosql/sql/parser/AstBuilder.java/AstBuilder/visitDropColumn
class AstBuilder:    @Override
    public Node visitDropColumn(SqlBaseParser.DropColumnContext context)
    {
        return new DropColumn(getLocation(context), getQualifiedName(context.tableName), (Identifier) visit(context.column));
    }