If I say this:
If I am sleeping when he will be coming wake me up, please.
Will it be correct phrase or I should say another way?
If I say this:
If I am sleeping when he will be coming wake me up, please.
Will it be correct phrase or I should say another way?
If I am sleeping when he will be coming wake me up, please.
Don't use this. It means "He is not here. He is coming. Wake me up." For example, if your brother calls your mother and says "I will be home on Saturday," you want your mother to come and wake you immediately, even if it is Monday!
If you do want to say that, use:
If you find out when he is coming while I'm sleeping, wake me up, please.
But as the commenters pointed out, what you probably want is:
If he arrives while I'm sleeping, please wake me up.
Or perhaps:
Please wake me up before he gets here, if I'm sleeping.
Which implies you want a warning so you have enough time to get ready.