When I perform `SELECT * FROM table` I got results like below:

```
1 item1 data1
2 item1 data2
3 item2 data3
4 item3 data4

```

As you can see, there are dup records from column2 (item1 are dupped). So how could I just get result like this:

```
1 item1 data1
2 item2 data3
3 item3 data4

```

Only one record are returned from the duplicate, along with the rest of the unique records.