In my `PostgreSQL` database, I have a table with two text values, `t1` and `t2`:

```
|   id   |   t1   |   t2   |  
|   1    |  abcd  |   xyz  |  
|   2    |  aazz  |   rst  |  
|   3    |  fgh   | qwerty |  

```

I would like to swap the values of the columns `t1` and `t2` for every row in the table in a way that, using the above example, this would be the result:

```
|   id   |   t1   |   t2   |
|   1    |  xyz   |   abcd |
|   2    |  rst   |   aazz |
|   3    | qwerty |   fgh  |

```

Also, let's suppose the values from all rows with id=4 onwards (4, 5, 6...) are already correct, is it possible to filter which rows I want to swap?  

I've tried [this](https://stackoverflow.com/questions/37649/swapping-column-values-in-mysql) (for MySQL Databases) but none of the solutions worked.