CREATE TABLE categories (
  name TEXT PRIMARY KEY COLLATE NOCASE,
  active INTEGER NOT NULL DEFAULT 1 CHECK(active IN (0,1)),
  created_at INTEGER NOT NULL
);
INSERT OR IGNORE INTO categories(name,active,created_at)
SELECT DISTINCT trim(category),1,0 FROM tasks WHERE trim(category)<>'';
INSERT OR IGNORE INTO categories(name,active,created_at) VALUES
('Na start',1,0),('Pomysły',1,0),('Opinia',1,0);