从SQL Server中的datetime列计算每个月的datetime条目

Question

I have a table with timestamps and I want to count the total number of timestamps for each month. I have the following script returning the results. Is there a simpler way to do this?

select 
    substring(convert(varchar(12), dt_create, 112), 0, 7) as month,
    count(substring(convert(varchar(12), dt_create, 112), 0, 7)) as signups
from 
    table_name
group by 
    substring(convert(varchar(12), dt_create, 112), 0, 7)
order by 
    1

Output

month   signups
----------------
201705  5959
201706  9782
201707  13663
201708  7385

Answer 1

Characters values are slower, you may see an increase in performance by trying this.

SELECT      Year = YEAR( dt_create ),
            Month = MONTH( dt_create ),
            signups = COUNT( dt_create )
  FROM      table_name
  GROUP BY  YEAR( dt_create ),
            MONTH( dt_create )
;