1
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Just as we have unset to drop a field, we also can rename it,

2
00:00:07,950 --> 00:00:15,030
so if we look back into our data, let's say age is something we want to rename to total age.

3
00:00:15,060 --> 00:00:19,190
Well what we could do is we could again update many,

4
00:00:19,320 --> 00:00:26,340
now I will actually just use empty curly braces to select all documents in the collection and then to

5
00:00:26,340 --> 00:00:34,890
rename a field, there is the rename operator. The rename operator takes a document as a value where you

6
00:00:34,890 --> 00:00:37,970
then specify the field name you want to rename,

7
00:00:37,980 --> 00:00:46,360
so in our case here, that is age and then as a string, the new field name, total age. If you now hit enter,

8
00:00:46,380 --> 00:00:50,250
you'll see three modifications were made,

9
00:00:50,550 --> 00:00:53,310
why three if we found four elements?

10
00:00:53,310 --> 00:00:55,640
Well Max never had an age,

11
00:00:55,740 --> 00:01:02,990
so if I now find all users, we see total age for Chris, total age for Anna, total age for Manuel and Max

12
00:01:03,000 --> 00:01:06,730
never had an age field and therefore it was also not renamed,

13
00:01:06,750 --> 00:01:07,920
it was never there

14
00:01:07,950 --> 00:01:11,880
and as you saw, it will then also not be added because what would be the value?

15
00:01:11,870 --> 00:01:15,060
We didn't specify a value, we just renamed it.

16
00:01:15,060 --> 00:01:18,360
If you wanted to add an age field to Max, you would do that with set.