SQL Server 2019

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CREATE TABLE Data (customer_Num  int , Channel_Id  Varchar(50) ,  Branch_Code  int)
INSERT INTO Data
VALUES (1, 'I', 1000)
  ,(1, 'Y', 1001)
  ,(1, 'L', 1002)
  ,(2, 'I', 1005)
  ,(2, 'Y', 1006)
  ,(2, 'L', 1007)
6 rows affected

SELECT customer_num
  ,p.I AS I_Branch_Code
  ,p.Y AS Y_Branch_Code
  ,p.L AS L_Branch_Code
FROM
(
  SELECT customer_num
    ,Channel_Id
    ,Branch_code
  FROM Data
)s
PIVOT
(
  MAX(Branch_Code) FOR Channel_Id IN ([I], [Y], [L])
) p


customer_num
I_Branch_Code
Y_Branch_Code
L_Branch_Code


1
1000
1001
1002

2
1005
1006
1007