Question

I have a scenario here where i am running 2 separate update queries.
How can I combine those into a single query by use of case?

UPDATE TABLE1 SET ACTV_IND = 0
WHERE NAME IN (
  select NAME
  from TABLE1
  where SID = 'child'
  group by NAME
  having MAX(CAST(ACTV_IND AS INT)) =0
)
AND SID = 'parent'

UPDATE TABLE1 SET ACTV_IND = 1
WHERE NAME IN (
  select NAME
  from TABLE1
  where SID = 'child'
  group by NAME
  having MAX(CAST(ACTV_IND AS INT)) =1
)
AND SID = 'parent'

Answer 1

Q1: I think this might be the solution

  ACTV_IND =  MAX(CAST(ACTV_IND AS INT)) 

Q2: It is possible to use join for update

UPDATE T1 SET T1.C1 = :val1 FROM TABLE1 T1 join TABLE T2 ON T1.KEY1 = T2.KEY2

I would try something this like this, assuming that MAX(CAST(ACTV_IND AS INT)) will return 0 or 1

WITH DATA_SOURCE (NAME, VAL) AS (
 select NAME, MAX(CAST(ACTV_IND AS INT)) VAL from TABLE1 where SID = 'child' group by NAME
)
UPDATE TABLE1
 SET ACTV_IND  = DS.VAL 
FROM TABLE1 T1 JOIN DATA_SOURCE DS ON T1.NAME = DS.NAME
WHERE T1.SID = 'parent'
GO