SELECT A SPECIFIC VALUE OF FILED IN DB

Hello,

Firstly,i used to Bonita Studio 5.10 I create a new Connector with db-MySQL and i complete correct database access information(database,host,username,password)

In the next step,i want to enter a query.

import com.mysql.jdbc.Driver; import groovy.sql.Sql; import java.text.SimpleDateFormat;

//step1

"SELECT numberApplication,name,date_of_apply,status_apply FROM candidate_customer WHERE username=kt;" // (Search on specific usename.Without 'WHERE',the code execute excellent)

//username is field of db

I want to connect with db and return username,which is 'kt'. kt is a variable of bonita,which is defined by default 'katerina'

How can do it? Should i define a variable kt again in step1; such as kt='katerina'; OR kt=kt.toString(); Thank in advnace