SELECT

'Table Name' = ST.[name]

, 'Column Name' = SC.[name]

, 'Default Value' = SD.definition

, 'Constraint Name' = SD.[name]

, DROP_SCRIPT = 'ALTER TABLE [' + SCHEMA_NAME(SD.[schema_id]) + '].[' + OBJECT_NAME(SD.[parent_object_id]) + '] DROP CONSTRAINT [' + SD.[name] + ']; '

, ADD_SCRIPT = 'ALTER TABLE [' + SCHEMA_NAME(SD.[schema_id]) + '].[' + OBJECT_NAME(SD.[parent_object_id]) + '] ADD CONSTRAINT [' + SD.[name] + '] DEFAULT ([dbo].[GetLoginName]()) FOR [' + SC.name + ']'

FROM

sys.tables ST

INNER JOIN sys.syscolumns SC ON ST.[object_id] = SC.[id]

INNER JOIN sys.default_constraints SD ON ST.[object_id] = SD.[parent_object_id] AND SC.colid = SD.parent_column_id