Please read the first article in my signature about posting these types of questions to the forum. I have added the tables and some sample data for you and using the window function ROW_NUMBER() to solve the issue. Let me know if this works for you:drop table ATTRIBUTE_TRANS;

drop table WS_Table;

go

create table ATTRIBUTE_TRANS (

ID_NUM int

,Attrib_seqint)

create table WS_Table (

id_num int

,attribute_cde int

);

insert ATTRIBUTE_TRANS

values (1,2)

,(2,1);

insert WS_Table

values (1,1)

, (2,1)

, (1,2)

, (3,1);

SELECT w.id_num,

ISNULL((SELECT MAX(a.ATTRIB_SEQ)

FROM dbo.ATTRIBUTE_TRANS a

WHERE w.ID_NUM = a.ID_NUM

GROUP BY a.ID_NUM

)+ROW_NUMBER() over (partition by w.id_num order by w.id_num), 1) AS MAX_SEQ_NUM

,attribute_cde

,'ADMIN'

,'attribute_insert'

,CURRENT_TIMESTAMP

FROM WS_Table w

EDIT: I forgot to add partition by in ROW_NUMBER