In oracle I would like to check if a record exists before insert then if exist update the record.

This site was really helpful. Is there a better method to do what I am trying to do? Why did the second method not work?

https://www.geeksforgeeks.org/how-to-check-if-a-row-already-exists-in-plsql/

DECLARE
  v_count NUMBER;
BEGIN
  SELECT COUNT(*)
  INTO v_count
  FROM employees
  WHERE employee_id = 100;

  IF v_count > 0 THEN
    DBMS_OUTPUT.PUT_LINE('Row exists in employees table for employee_id = 100');
  ELSE
    DBMS_OUTPUT.PUT_LINE('Row does not exist in employees table for employee_id = 100');
  END IF;
END;

DECLARE
  v_exists BOOLEAN := FALSE;
BEGIN
  SELECT 'TRUE'
  INTO v_exists
  FROM dual
  WHERE EXISTS (
    SELECT 1
    FROM employees
    WHERE employee_id = 101
  );

  IF v_exists THEN
    DBMS_OUTPUT.PUT_LINE('Row exists in employees table for employee_id = 101');
  ELSE
    DBMS_OUTPUT.PUT_LINE('Row does not exist in employees table for employee_id = 101');
  END IF;
END;

Initial setup

CREATE TABLE people(
  id int primary key,
  name varchar(55),
  status int,
  phone varchar(55)
);

INSERT INTO people (id, name, status, phone) 
  WITH names AS (
    SELECT 1 id, 'jOHN' name, 1 status, '214-444-1234' phone     FROM dual UNION ALL
    SELECT 2, 'John', 1, '214-444-1234'    FROM dual UNION ALL 
    SELECT 3, 'Mary', 0, '555-111-1234'    FROM dual UNION ALL 
    SELECT 4, 'Mary', 0, '555-111-1234'    FROM dual UNION ALL 
    SELECT 5, 'Jeff', 0, '214-222-1234'    FROM dual UNION ALL 
    SELECT 6, 'Jeff', 0, '214-222-1234'    FROM dual UNION ALL 
    SELECT 7, 'Bill', 1, '817-333-1234'    FROM dual UNION ALL 
    SELECT 8, 'Bill', 1, '817-333-1234'    FROM dual UNION ALL 
    SELECT 9, 'Bob' , 1, '214-555-1234'    FROM dual UNION ALL 
    SELECT 10, 'Bob' , 1, '214-555-1234'    FROM dual UNION ALL 
    SELECT 11, 'Ruth',     1,      'Mrs'    FROM dual UNION ALL 
    SELECT 12, 'Isabelle', 2,      'Miss'   FROM dual UNION ALL 
    SELECT 13, 'Justin',   3,     'Master' FROM dual UNION ALL 
    SELECT 14, 'Lisa',     4,      'Dr'     FROM dual 
  ) 
  SELECT * FROM names;

This worked on my database.

DECLARE
    v_count NUMBER;
BEGIN
    -- Check if a row exists based on specific conditions
    SELECT COUNT(*)
    INTO v_count
    FROM people
    WHERE id = 1;

    IF v_count > 0 THEN
        -- Row exists
        -- Perform necessary actions
        UPDATE people SET name = 'jack' WHERE id = 1;

    ELSE
        -- Row does not exist
        -- Perform necessary actions
        INSERT INTO people VALUES
        (1, 'Josh', 1, '214-444-1235');
    END IF;
END;

Surprisingly did not work on dbfiddle.

ORA-06550: line 21, column 3:
PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:

   ; <an identifier> <a double-quoted delimited-identifier>
The symbol ";" was substituted for "end-of-file" to continue.

I was unable to make the second method work on my database or dbfiddle.

DECLARE
  v_exists BOOLEAN := FALSE;
BEGIN
  SELECT 'TRUE'
  INTO v_exists
  FROM dual
  WHERE EXISTS (
    SELECT 1
    FROM people
    WHERE id = 1
  );

  IF v_exists THEN
    UPDATE people SET name = 'jack' WHERE id = 1;
  ELSE
    INSERT INTO people VALUES
    (1, 'Josh', 1, '214-444-1235');
  END IF;
END;

This was my database error message.

[Error] Execution (71: 8): ORA-06550: line 5, column 8:
PLS-00382: expression is of wrong type

This was dbfiddle error message.

ORA-06550: line 19, column 3:
PLS-00103: Encountered the symbol "end-of-file" when expecting one of the following:

   ; <an identifier> <a double-quoted delimited-identifier>
The symbol ";" was substituted for "end-of-file" to continue.

https://dbfiddle.uk/b7z78r_u