Highlight selected text and show next time

Question

I am interested in saving text when user selects any text anywhere on a web page that text has to be highlighted and has to save that text as a string in DataBase.

when same user saw same page next time text has to be highlighted as done previously by him.

If anyone knows a simple elegant way to do this I would really appreciate it, but I'll take any solution at this point. Even if you can point me in the right directions that would be appreciated. Thanks in advance.

I m tried with this code 

function highlight() {

var range, sel;

// IE case

if (document.selection && document.selection.createRange) {

range = document.selection.createRange();

//range.execCommand("Bold", false, null);

range.execCommand("BackColor", "false", "yellow");

txt = document.selection.createRange().text;

} else if (window.getSelection) {

// Non-IE

sel = window.getSelection();

if (sel.rangeCount && sel.getRangeAt) {

range = sel.getRangeAt(0);

alert(range);

}

document.designMode = "on";

if (range) {

sel.removeAllRanges();

sel.addRange(range);

alert(range);

}

// document.execCommand("Bold", false, null);

document.execCommand("BackColor", "false", "yellow");

document.designMode = "ofx f";

}

}

</script>

but using this code i m getting problem in firefox but it works fine in IE,Chrome and also i have show highlight the text when same user open same page next time For that i have to store text in my database.