oracle按時間分組查詢

• 按年查詢：
  

  select count(*), to_char(column_name,'yyyy') from table_name group by  to_char(column_name,'yyyy');

• 按月查詢：

        select count(*), to_char(column_name,''yyyy-mm'') from table_name group by to_char(column_name,''yyyy-mm'');

• 按周查詢：

        select count(*), to_char(column_name,'iw') from table_name group by  to_char(column_name,'iw');