I have the following table:
ID - Reference - Number
1 - null - 9000
2 - null - 9001
3 - 123 - 9002
4 - 123 - 9003
5 - null - 9004
6 - null - 9005
7 - null - 9006

I need to return the next (TOP 3) consecutive rows where Reference is null. In this case, 9004-9006. I assume a "having" clause but I'm not sure how to do this.
Thanks for any help.

how do you define "next" here?

I need the next available group of numbers where the reference column is null. In this case, the top 3 rows (where reference is null) would be 9000-9001, 9004. I need it to be 9004-9006. Basically, to fulfill the request with the first complete available range for a given quantity.

i think maybe you didn't understand my question

ID - Reference - Number
1 - null - 9000
2 - null - 9001
3 - 123 - 9002
4 - 123 - 9003
5 - null - 9004
6 - null - 9005
7 - null - 9006
8 - 123 - 9007
9 - null - 9008
10 - null - 9009
11 - null - 9010

which three are "next"?

are you always starting with the lowest ID in the table?

the first group of 3 available (the lowest).
9004-9006

Got the solution here:

Select next available consecutive range