sql server select a specific letter of string and verify string code example

Example: check if string contains substring sql

Declare @mainString nvarchar(100)='Amit Kumar Yadav'  
---Check here @mainString contains Amit or not, if it contains then retrun greater than 0 then print Find otherwise Not Find  
if CHARINDEX('Amit',@mainString) > 0   
begin  
   select 'Find' As Result  
end  
else  
    select 'Not Find' As Result