Feeling I am doomed

Question

Good morning, I am sending this mail seeking advice for my career. I have been working in web development using asp.net and SQL Server for the past 8 years but I am a single developer in my company and the projects I do are not that big, so, I got the feeling that I am outdated and not up to the standards of web development anymore. I am trying to study online courses and read recent news but due to the fact that I am not within a team i feel separated from the developers environment. I thought of quitting for another company but i found that I can't stand against powerful candidates in my field. Now I am starting to lose interest and just sticking to the routine of doing what I know without trying to update myself as I am feeling its now useless. Thanks in advance for your help.
I want to add that i don't have any Microsoft certificates .

Answer 1

i solved it 

Select Cast(SUM((O_ttotal + P_vatto) * (P_totdis / 100)) As Decimal(9,2)) As TotalDiscount From PRO_BILL

Answer 2

@Abrar that i also know, in this way i get two answers i want the whole total of (A+B+C) not (A+B) and C

Answer 3

HI, when you are using the aggregate sql function then you have to define the group by clause.

like 
cmd = new SqlCommand("Select (SUM(P_ttotal)+SUM(P_vatto)* (P_totdis)/100) as dis  from PRO_BILL group by P_totdis", conn);