Pros:
- it is convenient to type and read numbers this way;
- Ada, Perl, C++, Go and Rust already support that;
- can support thousands as well as lakhs and crores;

Cons:
- standard SQL does not have this support;
- PostgreSQL treat `SELECT 1_000_000` as number one with `_000_000` alias: http://sqlfiddle.com/#!17/0a28f/400
- C++ has `1'000'000` instead of `1_000_000`;

What do you think?

{
    auto assignment = std::make_shared<ASTAssignment>();
    node = assignment;
    ParserIdentifier p_identifier;
    ParserToken s_equals(TokenType::Equals);
    ParserExpression p_expression;
    ASTPtr column;
    if (!p_identifier.parse(pos, column, expected))
        return false;
    if (!s_equals.ignore(pos, expected))
        return false;
    ASTPtr expression;
    if (!p_expression.parse(pos, expression, expected))
        return false;
    tryGetIdentifierNameInto(column, assignment->column_name);
    if (expression)
        assignment->children.push_back(expression);
    return true;
}
}