Db2 Developer-C 11.1

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--create table_1
CREATE TABLE MD001 (MRN, Name, Address) AS 
(
VALUES 
  (1, 'NameName1', 'Add1')
, (2, 'NameName2', 'Add2')
, (3, 'NameName3', 'Add3')
) WITH DATA
CREATE TABLE PATIENT (CaseNo, FName, MName, LName) AS 
(
VALUES 
  ('1', 'F', 'M', 'L')
, ('2', '', '', '')
) WITH DATA
with U as (
select count (1) as dummy from new table(  
update MD001 m 
SET NAME = (
        SELECT FName || ' ' || Mname || ' ' || LName
        FROM PATIENT
        WHERE fname <> '' AND mname <> '' AND lname <> ''
        )
  where m.MRN  = (SELECT caseno FROM patient WHERE caseno = m.MRN)
  ))
select * from MD001


MRN
NAME
ADDRESS


1
F M L
Add1

2
F M L
Add2

3
NameName3
Add3