what does order by desc do in sql code example

Example 1: order by sql

//this_for_descending_order.. 
 SELECT * FROM TableName ORDER BY columnName DESC;
 // this_for_ascending_order..
SELECT * FROM TableName ORDER BY columnName ASC;

Example 2: sql order

SQL order of execution defines the
execution order of clauses.

-Select
It starts execution with 
-from  (Choose and join tables to get base data)
after from
-where ( filters base data )
-group by (Aggregates base data)
-having (filters aggregated data)
-select (returns final data)
-order by (sorts the final data)
-limit (limits the returned data to a row count)

Only select and from are mandatory