Different types of users logging in to Android App with SQLite Database

Question

Sorry if this is a stupid question but I am new to Android Development. I am trying to create a login screen which will direct doctors to a one activity and nurses to another activity when they login. This does not seem to work. I have put code into the login.java class:

btLogin.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                String email = loginemail.getText().toString();
                String password = loginpassword.getText().toString();
                Boolean Chkemailpass = db.emailpassword(email, password);
                if(Chkemailpass == true) {
                    Cursor typeofuser;
                    typeofuser = db.checkUser(loginemail.getText().toString()); //get user type from database
                    if(typeofuser.equals("Nurse")) {
                        Intent mainintent = new Intent(Login.this, NurseHome.class);
                        startActivity(mainintent);}
                    else if (typeofuser.equals("Doctor")){
                        Intent intent = new Intent(Login.this, DoctorHome.class);
                        startActivity(intent);}
                    }
                    else
                    Toast.makeText(getApplicationContext(),"Wrong email or password", Toast.LENGTH_SHORT).show();
                }
        });

    }
}

And I also have this code in the databasehelper class relating to the usertype:

public Cursor checkUser(String email) {
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor res = db.rawQuery("SELECT TYPEOFUSER from user_table WHERE EMAIL=email", null);
        return res;
     }

All help would be appreciated, thank you.

Answer 1

The argument email of checkUser() is a string, so in your sql statement it should be enclosed inside single quotes like this:

SELECT TYPEOFUSER from user_table WHERE EMAIL = 'email'

but the correct way to pass parameters to rawQuery() is with the use of ? placeholders and the use of the 2nd argument as an array of string parameters (instead of null).
Also don't return the Cursor, but the type of user as a String from checkUser().
So change to this:

public String checkUser(String email) {
    String result = "";
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor res = db.rawQuery(
        "SELECT TYPEOFUSER from user_table WHERE EMAIL = ?", 
        new String[] {email}
    );
    if (res.moveToNext()) {
        result = res.getString(0);
    }
    res.close();
    return result;
}

and instead of:

Cursor typeofuser;
typeofuser = db.checkUser(loginemail.getText().toString());

use this:

String typeofuser = db.checkUser(loginemail.getText().toString());