将具有相同id的null行组合在一起最充分的方法是什么:
Having this table:
| UserID | FNAME | LNAME |
|--------|-------|-------|
| 1 | NULL | NULL |
| 1 | jhon | NULL |
| 1 | NULL | doe |
| 2 | NULL | NULL |
| 2 | Jarry | NULL |
| 2 | NULL | Lauf |
want to get:
| UserID | FNAME | LNAME |
|--------|-------|-------|
| 1 | jhon | doe |
| 2 | Jarry | Lauf |
按用户聚合,然后取两个名称列的最大值:
SELECT UserID, MAX(FNAME) AS FNAME, MAX(LNAME) AS LNAME
FROM yourTable
GROUP BY UserID;