Obtain count for duplicates in two tables oracle sql - sql

Question

I have a database and I will primarily focus on two table. Table 1 has emp_id as primary key
Table 1 store access info for each employee. I am tasked to count how many time an employee goes into a room..
Table 1
emp_id time_in time_out, other columns etc
1111 3:00 3.30
2222 1:00 1:10
3333 2:00 2:45
4444 7:00 5:00
table 2
sequence_no, emp_id, time, access type, other columns etc
Table 2 has multiple entries of enties
sequence_no, emp_id, time, access type
10000 1111 3:00 granted
10221 1111 3:23 granted
19911 2222 x
12122 1111 x
23232 3333
I have written sQl query that display joins the two tables,
but at the moment I am trying to add a column that either sums total entries (due to the sequence number, my query is returning multiple rows)
select e.emp_id,a.sequence_no,count(sequence_no) from employee, access a where e.emp_id = a.emp_id
group by e.emp_id having count t(1) > 1
output should look like
emp_id, sequence number, time in/out , total_counts
1111 10000 3:30 5
1111 12122 3:30 5
2222 19911 2:20 19
within the results, I need the sequence number which will cause duplicate emp_id, but the total for each ID should be the same accross;

Answer 1

you don't need to group anything:
select
e.emp_id,
a.sequence_no,
count(sequence_no) over (partition by e.emp_id) as total_counts
from employee, access a
where e.emp_id = a.emp_id
If you want to filter those emps with less than two entries:
select *
from
(
select
e.emp_id,
a.sequence_no,
count(sequence_no) over (partition by e.emp_id) as total_counts
from employee, access a
where e.emp_id = a.emp_id
)
where total_counts >= 2;
If you want to group by emp, in Oracle(I don't know if the syntax is ok in sqlserver) you can use keep:
select
e.emp_id,
max(a.sequence_no) keep (dense_rank first order by time desc), --last sequence
count(sequence_no)
from employee, access a
where e.emp_id = a.emp_id
group by e.emp_id
having count(*) > 1;