If -else statement

[bharti]

if(patient_age >= 0 AND patient_age <= 18, '0-18',
if(patient_age >= 19 AND patient_age <= 65, '19-65',
if(patient_age >= 66, '66 above','unknown')
)
)

missing paranthesis error

[Sayed_Mannan]

Hi, I don't find any error in your code, but you can try this 

if(patient_age >= 0 AND patient_age <= 18, '0-18',
	if(patient_age >= 19 AND patient_age <= 65, '19-65',
		if(patient_age >= 66, '66 above','unknown')
	)
)