How to insert values into database using queries using entity manager, persistence using a java class?

Question

I want to insert data into a table using the following code

    public User registerUser(String usr, String pwd) {

    u=em.find(User.class,usr);
    if(u!=null)
    {
        return null;
    }
    String query1 = "insert into users values('" + usr + "','" + pwd +"')";
    Query q = em.createQuery(query1);
    u=em.find(User.class,usr);
    return u;

}

here 'u' is the object of User class and em is EntityManager.

I get this following exception:

Servlet.service() for servlet action threw exception org.hibernate.hql.ast.QuerySyntaxException: expecting OPEN, found 'values' near line 1, column 19 [insert into users values('pawan','am')]

Answer 1

Try

public User registerUser(String usr, String pwd) {

    u=em.find(User.class,usr);
    if(u!=null)
    {
        return null;
    }

    //Now saving...
    em.getTransaction().begin();
    em.persist(u); //em.merge(u); for updates
    em.getTransaction().commit();
    em.close();

    return u;
}

If the PK is Identity, it will be set automatically in your persisted class, if you are using auto generation strategy (thanks to David Victor).

Edit to @aman_novice comment: set it in your class

//Do this BEFORE getTransaction/persist/commit
//Set names are just a example, change it to your class setters
u.setUsr(usr);
u.setPwd(pwd);

//Now you can persist or merge it, as i said in the first example
em.getTransaction().begin();
(...)

About @David Victor, sorry I forgot about that.

Answer 2

You're not using SQL but JPAQL, there is no field-based insert. You persist object rather than inserting rows.

You should do something like this:

public User registerUser(String usr, String pwd) {
    u=em.find(User.class,usr);
    if(u!=null)
    {
        return u;
    }
    u = new User(usr, pwd);
    em.persist(u);
    return u;
}