mysql - how to display error instead of throw err in nodejs - mysql

Question

I have put some constraints in my mysql table and thus when a duplicate value is entered, it throws an error and the server shuts down.
What I want instead is that the server should keep running and I should display the error to the end user, so they know they are inputting a duplicate value and hence the error.
how do I do that?
here's my code.
i tried to change the code a bit by putting the render statement in the else option. i.e if it doesnt throw the error then page is rendered otherwise It would do a res.send(err).
is that possible??
here's the code for this
connection.query("INSERT INTO attendance_details(month_year,uan,name,days_present,real_basic_salary,other_allowances,gross_salary,ptax) VALUES ?",
[finalData], function(err) {
if (err){
throw err;
res.send(err);
}else{
var attendanceData = {monthyear :monthFromHTML,rows:rowsLength,uanarr:uanArr,designationarr:designationArr,
namearr:nameArr,finaldata:finalData,realbasicsalary:realBasicSalary,realgrosssalary:realGrossSalary,ptax:pTax,advance:advance};
//put database query for inserting values here
res.render('attendance-data.ejs', attendanceData);
}
connection.end();
});