SQL - Display Name ID from Consecutive Occurrences of values in a Table - sql

Question

I have a table created, as an example 'Table1', see below;
Name Year
John 2003
Lyla 1994
Faith 1996
John 2002
Carol 2000
Carol 1999
John 2001
Carol 2002
Lyla 1996
Lyla 1997
Carol 2001
John 2009
Based on the above table, I have summarised my findings.
Carol participated for 4 years in a row; 1999, 2000, 2001, 2002
John participated for 3 years in a row; 2001, 2002, 2003 – John also participated in 2009, but this does not count as part of the streak.
Lyla participated in 1994, 1996, 1997 but these were not three consecutive years.
Faith participated only 1 time.
What I am looking to do is write a SQL query where only the Name Id in the table are displayed where the users have participated for 3 consecutive years or more, so I should only be getting the names of only 'Carol' and 'John' based on the above.
I am not exactly sure how to write this and would hope that someone could guide me.
I have only come up with a short and basic start like the one below, but in all honesty I am not sure that is even the correct way to go about it.
Select Name From Table1
Where Year = ?
Order by Name asc
Group by Year

Answer 1

Assuming you have one row per person per year, you can use lag() and select distinct:
select distinct name
from (select t.*,
lag(year, 2) over (partition by name order by name) as prev2_year
from table1 t
) t
where prev2_year = year - 2;
This simply looks back two rows for each name and compares the year on that row to the year on the current row. If there are three years in a row, then that year is exactly year - 2.
You could also do this with joins, but the above probably performs better:
select distinct t1.name
from table1 t1 join
table1 t1_1
on t1.name = t1_1.name and
t1.year = t1_1.year + 1 join
table1 t1_2
on t1.name = t1_2.name and
t1.year = t1_2.year + 2;

Answer 2

select
n1.name,
SUM(CASE WHEN n2.year is null then 0 else 1 end)+1 YearsInRow
from Table1 n1
left join Table1 n2 on n2.name=n1.name and (n2.year=n1.year+1 )
GROUP by n1.name
HAVING SUM(CASE WHEN n2.year is null then 0 else 1 end)+1 >=3
output:
name YearsInRow
---------- -----------
Carol 4
John 3