SQL Server: CPU utilization troubleshooting using DMVs

Run the following query to get the TOP 50 cached plans that consumed the most cumulative CPU. All times are in microseconds. This is not necessarily an exhaustive list. If a query is recompiled the details for that plan are removed; if there are further executions later, its cumulative stats in sys.dm_exec_query_stats start off at zero. If the procedure cache is flushed or SQL Server is restarted, all plans will be similarly affected.

SELECT TOP 50 qs.creation_time,
qs.execution_count,
qs.total_worker_time as total_cpu_time,
qs.max_worker_time as max_cpu_time,
qs.total_elapsed_time,
qs.max_elapsed_time,
qs.total_logical_reads,
qs.max_logical_reads,
qs.total_physical_reads,
qs.max_physical_reads,
t.[text],
qp.query_plan,
t.dbid,
t.objectid,
t.encrypted,
qs.plan_handle,
qs.plan_generation_num
FROM sys.dm_exec_query_stats qs
CROSS APPLY sys.dm_exec_sql_text(plan_handle) AS t
CROSS APPLY sys.dm_exec_query_plan(plan_handle) AS qp
ORDER BY qs.total_worker_time/qs.execution_count DESC;

For more information refer to this blog post by Jared Poché

SQL Server Vs Oracle: Handling of empty string and nulls.

In Oracle database empty string gets treated as null.

DECLARE v_name NVARCHAR2(16);
BEGIN
  
  v_name := 'xyz';
  IF( v_name != '') THEN
    dbms_output.put_line ('Valid comparison');
  ELSE
    dbms_output.put_line ('Impossible');
  END IF;  
  
  IF ('' IS NULL) THEN
    dbms_output.put_line ('Empty string as null');
  END IF;

END;


This is different from behaviour of SQL Server. SQL server treats empty string as not null.