sql server update field that contains nulls

[harrisw48]

Im trying to update a field that contains NULLS using the concatenate code below

dbo.[Current Extract].[field1] = isnull(dbo.[Current Extract].[field1], '') + dbo.[Current Extract].[field1] + '-1-'

The code appears to work but it doesnt update the field, it still contains NULLS where you would expect data.

Any ideas?

 

[SQL_Hell]

update table
set dbo.[Current Extract].[field1] = '''' + dbo.[Current Extract].[field1] + '-1-'
where dbo.[Current Extract].[field1] ISNULL