Question

I have two tables one to store a task and one to evaluate the task:

create table task(
  _id  integer primary key autoincrement,
  task text not null);

create table eval (
  _id    integer primary key autoincrement,
  taskid integer,
  eval   integer);

Some data:

INSERT INTO task VALUES (1,"A small job");
INSERT INTO task VALUES (2,"A easy job");
INSERT INTO eval VALUES (1,1,1);
INSERT INTO eval VALUES (2,1,2);
INSERT INTO eval VALUES (3,2,1);
INSERT INTO eval VALUES (4,2,2);

Then a view joining the two tables:

  CREATE VIEW status AS 
  SELECT eval._id   AS _id, 
  eval.taskid   AS taskid, 
  eval.eval     AS eval, 
  task.task 
  FROM task JOIN eval 
  ON task._id = eval.taskid;

SQLite Database Browser doesn’t support views. What’s a good database browser for android development on linux?

Secondly, consider this query: Select the highest evaluation on each task

SELECT s.task, s.eval 
FROM status AS s 
JOIN (
  SELECT task, MAX(eval) AS maxeval 
  FROM status 
  GROUP BY task
) AS pm ON s.task = pm.task AND s.eval = pm.maxeval;

Resulting in:

s.task       s.eval
A easy job   2
A small job  2

How do I implement this query in an Android app? I’ve tried to pack it into a Cursor android.database.sqlite.SQLiteDatabase.query method and its siblings without much luck.

Is there a way to just pass the SQL query as a string into the database and get a result set back?

Answer 1

• you can use SQLiteManager a firefox add-onn. It is a visual
  browser for sqlite database. I am using it and it is very nice.

• If you want to learn sqlite syntax, you can use this tutorial.

• You can use db.execSQL(sqlCommand) fore update, write and delete
  operations. For read operations you can use cursor =
db.rawQuery(sqlQuery, null);, where db is SQLiteDatabase‘s object.