Update Missing Data In Table I have a table with sample data set-up like below.  How can I update the missing data for the field rglname?  There will always only be ONE rglname assigned to region so I am not worried about duplicate values.  Below is DDL

Create Table #BlueBell
(
  ID int
  ,region varchar(100)
 ,rglname varchar(500)
)

Insert Into #BlueBell VALUES
(1, 'East', 'Bob')
,(2, 'East', NULL)
,(3, 'East', NULL)
,(4, 'West', 'Sam')
,(5, 'West', NULL)
,(6, 'South', NULL)
,(7, 'South', NULL)
,(8, 'South', NULL)
,(9, 'South', 'Mitch')


And desired output is:


  ID    Region  RGLName
  1   East    Bob
  2   East    Bob
  3   East    Bob
  4   West    Sam
  5   West    Sam
  6   South   Mitch
  7   South   Mitch
  8   South   Mitch
  9   South   Mitch
You can use the following update.

update #BlueBell set rglname = b.rglname
from #BlueBell a
inner join (
            select region, rglname
            from #BlueBell where rglname is not null
            ) b on a.region = b.region


Check your desired output here

select * 
from #BlueBell