Question

I’m trying a simple SQL Command wihtin my Android-App, to get the age of a selected Person:

public int getAge(){
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name =? " + MainActivity.selectedPerson.getText().toString(), null);
    int age = cursor.getInt(3);               // column with ages
    cursor.close();
    db.close();
    return age;
}

But when I run my app, it crashes when I call the function getAge(). I get the following Error:

SQLiteException: no such column: Max: , while compiling: SELECT * FROM persons WHERE name = Max

I don’t get it. There is the name “Max” in the table. What am I doing wrong? Thanks in advance.

Edit 2:
With this one:

Cursor cursor = db.rawQuery("SELECT name FROM persons WHERE name = '" + MainActivity.selectedPerson.getText().toString() + "'", null);

I get a different error:

08-27 19:43:47.573: E/AndroidRuntime(6161): android.database.CursorIndexOutOfBoundsException: Index -1 requested, with a size of 1

what does this mean?

Answer 1

You should consider using the selectionArgs parameter of rawQuery() to prevent SQL Injection Attacks:

Cursor cursor = db.rawQuery("SELECT * FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });

Also you only need one column so rather than wasting resources by selecting them all with *, you should just select the one column:

Cursor cursor = db.rawQuery("SELECT age FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });

Hope that helps!

---

All together it should look like:

public int getAge(){
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("SELECT age FROM persons WHERE name = ?", new String[] { MainActivity.selectedPerson.getText().toString() });

    int age;
    // Check if you have a valid result and move to the first row to read it
    if(cursor.moveToFirst())
        age = cursor.getInt(0);
    // Prevent a crash if there is no data for this name
    else
        age = 0;

    cursor.close();
    db.close();
    return age;
}