how to get data from input field in wordpress to retrieve data from database against user input

In word press plugin i tried to read user input from text field to fetch data from database against user input (text field). I tried to do it by Ajax technique but not successful yet. i google it and found some techniques which are given on following links

http://ift.tt/1AuZsTC

http://ift.tt/1EMcdfe

i develop plugin and write query to fetch data for specific input but now i'm confuse how to read and pass it to ajax and then display. actually i can do this in PHP and ajax techniques but that is not smart solution, i suppose if word press has some nice and smart solution to read input and then call some function to get that data.

other way i have is simply put button when user will press button then trigger java script function containing ajax code to bring required data.

can you share some food example.

via Chebli Mohamed