You cant work both the places full time

You cannot do so during course of your employment 

Even then you cannot start another company 

it would be ground for termination of your employment 

Yes then you can if you are a sleeping partner. 

Dear Sir/Madam,

You are suggested some of the companies provide second employment as well as the business dealings. You are required to check your offer letter, contract/agreement done with the present company and then you may proceed accordingly.

 entrepreneurs who want to launch their own startup while working with another employer need to check their internal employment guidelines. “Some companies do have zero tolerance, which means that an employee cannot take directorship or invest in another company or work on another project

You can start your company as long as your employment contract does not forbade you to do so. Employees in companies such as TCS, Infosys have explicit agreements in the employment contracts that says that you will not do any other work with any other business during the course of employment.

If you are one of the  entrepreneur, working on your startup idea on the side while you are gainfully employed and navigating the tricky fine print in your employment contract as you debate whether you should resign and start up or start up and then resign.

While at entrepreneurship while working for another company also gives rise to the bigger question of ownership of intellectual property developed during the course of employment. So, entrepreneurs should exercise caution while taking a call on how they will create that IP and ensure that they own the IP when they start up.

Yes without knowledge to your present owner.

Why not but not in your name.

No you cannot start your business while working full time on a job.

It purely depends on to the policy regulation which the present employer has in practice. Many companies don't allow their employees . 

legally, you cannot start. 

It all depends upon the agreement you have with the employer.

A side business can be run by you as you work in a private company. But the contract agreement between you and your employer is relevant. You shouldn't start a business which is similar to the one in which you are employed. Check the agreement.

- There is no provision in Labour Laws , that an employee working in a private employee cannot do separate business , like a government employee cannot enter into dual employment, i.e. cannot do financial, gain from another source, unless he is authorised in writing by the concerned department. 

-  Hence, you will have to follow the restriction & rules, which you have signed at the time of joining your position in the said company. 

- If there is no restriction for the same, or your offer letter/appointment letter does not say anything about the same, then you can legally start a company even not full time.