Merge or append two datasets

[Rayhan Islam]

Dear altruist I have problem, I have two dataset in following format

Dataset1
ID Age
1 17
2
3 19
4
5
6

Dataset2
ID Age
1 17
2 19
3 19
4 20
5 15
6 16
Here ID is a unique variable. I have dataset1 now I want to construct dataset2 after inputing corresponding id's value from another dataset. So what should I use merge or append? I have already used merge and append but not come up with the Dataset2 like table. Please help me.

[Carlo Lazzaro]

Rayhan:
welcome to the list.
It would seem a job for -merge-.
What went wrong?

[Rayhan Islam]

Thanks for your response. But the problem is when I do merge variable of age which was previously blank remain blank after merge.
Output showed that the data was merged but not shown in merged file "Age" column.

here is the code and output image.
[use dataset1, clear
merge 1:1 UniqueID using "dataset2", force]

[Carlo Lazzaro]

Rayhan:
is -Age- numerical in both datasets?

[Rayhan Islam]

No. Here I used age for example. But in my real dataset Age like variable is RID which is like "4V19053210" so when I use [destring RID, replace] it shows
"RID contains nonnumeric characters; no replace"
And my UniqueID also look like RID.
how can I make do conversion before merge?