if count value of the column is greater than 1, I want to print the count of the column else I want to print value in the field - sql

Question

I am writing a query which fetches details from different tables. In one column I want to print count value of a column. If the count value of the column is greater than 1, I want to print the count of the column else I want to print value in the field.
I want to build a query which will give me count of user_id from table 1 & 2. if the count user_id is greater than 1, then print count (user_id) else print value of user_id
Table:1
| user_id |
| John |
| Bob |
| Kris |
| Tom |
Table:2
| user_id |
| Rob |
query result should list count of table1 as it greater than 1. Table2 should list Rob as it is lesser than 2

Answer 1

You want to select user IDs (names actually) from a table. If it's just one row then show that name, otherwise show the number of entries instead. So, just use a CASE expression to check whether count is 1 or greater than 1.
You probably need CAST or CONVERT to turn the count number into a string, so the CASE expression always returns the same type (this is how CASE works).
select
case when count(*) > 1
then cast(count(*) as varchar(100))
else max(user_id)
end as name_or_count
from mytable

Answer 2

Window Functions come to mind but since your user_ids are not numbers, you'll run into an issue where you can't have two different data types in the same column. See how this works for you. Make sure to cast the varchar numbers back to integer if this script is part of a larger process.
with cte as
(select 'John' as user_id union all
select 'Bob' as user_id union all
select 'Kris' as user_id union all
select 'Tom' as user_id)
select distinct case when count(*) over() > 1
then cast(count(*) over() as varchar) else user_id end
from cte
with cte as
(select 'Rob' as user_id)
select distinct case when count(*) over() > 1
then cast(count(*) over() as varchar) else user_id end
from cte