UPDATE itemNotes
SET
  note = SUBSTR(note, 0, INSTR(LOWER(note), 'sometext')) || 'abc' || SUBSTR(note, INSTR(LOWER(note), 'sometext')+sometext_len)
WHERE
  INSTR(LOWER(note), 'sometext') >= 0;

While (SELECT * FROM itemNotes  WHERE note like "%sometext%") >1

    UPDATE itemNotes
    SET
      note = SUBSTR(note, 0, INSTR(LOWER(note), 'sometext')) || 'abc' || SUBSTR(note, INSTR(LOWER(note), 'sometext')+sometext_len)
    WHERE
      INSTR(LOWER(note), 'sometext') >= 0;
END

WITH b(x,y) AS
    (
        SELECT 1,2
        UNION ALL
        SELECT x+ 1, y + 1

    FROM b
    WHERE x < 20
) SELECT * FROM b;

There is SOmetext and also somETExt and more SOMETEXT and even more sometext

There is abc and also abc and more abc and even more abc

CREATE TABLE itemNotes (
    itemID INTEGER PRIMARY KEY,
    parentItemID INT,
    note TEXT,
    title TEXT,
    FOREIGN KEY (itemID) REFERENCES items(itemID) ON DELETE CASCADE,
    FOREIGN KEY (parentItemID) REFERENCES items(itemID) ON DELETE CASCADE
);

UPDATE itemNotes
SET
  note = SUBSTR(note, 0, INSTR(LOWER(note), 'sometext')) || 'abc' || SUBSTR(note, INSTR(LOWER(note), 'sometext')+sometext_len)
WHERE
  note LIKE "%sometext%";

UPDATE itemNotes
SET
  note = regex_replace('bsometextb',note,'abc')
WHERE
  note LIKE "%sometext%";