SQL Adding the total rows selected to every row

Example

SELECT your_columns, COUNT(*) OVER() as Ttl_Rows FROM your_data_set
idnameTtl_Rows
1example5
2foo5
3bar5
4baz5
5quux5

Instead of using two queries to get a count then the line, you can use an aggregate as a window function and use the full result set as the window.
This can be used as a base for further calculation without the complexity of extra self joins.