Select 每组只有最小值和最大值

Question

How to select only 1 of min and max value of tap_time = tap_type 1(min) and 0(max) heres my unfinished query. Hope someone can help me.

use RFIDEmployee_DB

select *
from  (
    select FK_student_ID, Tap_Type, FK_Terminal_ID, Student_No, Last_Name, First_Name, Middle_Name, Tap_Time    
    from tbGateEntry
    inner join tbStudentInfo on tbGateEntry.FK_student_ID = tbStudentInfo.ID
) t    
order by Last_Name , Tap_Time

Answer 1

Rank function could help you choose first 1 by each type, change column name based on your requirement

use RFIDEmployee_DB

select *
from  (
    select FK_student_ID, Tap_Type, FK_Terminal_ID, Student_No, Last_Name, First_Name, Middle_Name, Tap_Time, ROW_NUMBER() OVER (PARTITION BY Tap_Type ORDER BY Tap_Time) R   
    from tbGateEntry
    inner join tbStudentInfo on tbGateEntry.FK_student_ID = tbStudentInfo.ID
) t
where R = 1   
order by Last_Name , Tap_Time