In my application two fields are the user id and user name,i want to show the user name and user id along with other details in a html table.
user id is a numeric dropdown menu and user name is text only.How can i show the specfic record in that table for that user which i have selected in both of the fields ,how i can fetch data from backend User table?am using html,css and javascript, Any suggestion would be grateful!Thanks..

You wouldn't want to use a client-side language like JavaScript to fetch backend data. For this you should look into a backend language like PHP (recommended), Python, C#, etc...

unless you make a 2 dimensional array thats hard-coded into the JavaScript and not an external source/file.