select o.name, *
from sys.columns c
inner join sys.objects o on o.object_id = c.object_id
where c.Name = N'COLUMN_NAME_TO_FIND'
--get all with table row count
CREATE TABLE #foo(name varchar(128),rows int)
DECLARE @objectName nvarchar(128)
DECLARE cursorTables CURSOR FOR
select o.name
from sys.columns c
inner join sys.objects o on o.object_id = c.object_id
where c.Name = N'u_username'
OPEN cursorTables
FETCH NEXT FROM cursorTables INTO @objectName
WHILE @@FETCH_STATUS = 0
BEGIN
INSERT INTO #foo
EXEC ('SELECT ''' + @objectName + ''' as NAME,COUNT(*) FROM ' + @objectName)
FETCH NEXT FROM cursorTables INTO @objectName
END
CLOSE cursorTables
DEALLOCATE cursorTables
SELECT * FROM #foo ORDER BY rows DESC
DROP TABLE #foo