Postgres error updating column data

Solution 1:

There is no need to wrap table name in double quote "employee", and use single quotes for column values

UPDATE employee   
   SET first_name='ok', last_name='pk', email='ooo', phone='000'
 WHERE employee_id = 1;

See Working Example

Try below sql:

 UPDATE employee
   SET first_name='ok', last_name='pk', email='ooo', phone='000'
 WHERE employee_id = 1;

Table name was wrapped in double quotes which is not allowed.