加入select語句中的額外重複記錄

Question

我有2個表，「read_barcodetolid」和「serial_barcode」。他們都有ordernum領域的共同點。我要選擇行，不希望有重複的值， 起初我用這個查詢：

SELECT distinct(t1.ordernum) 
       , t1.tarikh, 
        t2.city, 
        t2.officeNum, 
        t2.provience 
     FROM read_barcodetolid t1 
     join serial_barcode t2 on t1.ordernum=t2.ordernum 

它正常工作與剛剛ORDERNUM領域。但是當我添加另一個像城市的字段時，它會創建一些重複記錄。

然後我寫了這一個：

SELECT DISTINCT (
     SELECT DISTINCT TOP (1) ordernum 
     FROM read_barcodetolid 
     WHERE (ordernum = seri.ordernum) 
     ORDER BY ordernum DESC 
     ) AS ordernum, 
    (
     SELECT TOP (1) seri.officeNum 
     FROM read_barcodetolid AS read_barcodetolid_2 
     WHERE (ordernum = seri.ordernum) 
     ORDER BY ordernum DESC 
     ) AS officeNum, 
    (
     SELECT TOP (1) provience 
     FROM serial_barcode 
     WHERE (ordernum = seri.ordernum) 
     ) AS provience, 
    (
     SELECT TOP (1) city 
     FROM serial_barcode AS serial_barcode_1 
     WHERE (ordernum = seri.ordernum) 
     ) AS city, 
    (
     SELECT TOP (1) tarikh 
     FROM read_barcodetolid AS read_barcodetolid_1 
     WHERE (ordernum = seri.ordernum) 
     ) AS tarikh 
FROM serial_barcode AS seri 
WHERE (ordernum IS NOT NULL) 
ORDER BY tarikh DESC 

它返回的結果，但在最後給出了一些空的記錄，當我使用「其中ORDERNUM IS NOT NULL」它不工作

我能做些什麼？ 是更好的解決方案來擺脫額外的重複記錄？

Answer 1

嘗試子句中使用組

SELECT t1.ordernum, MAX(t1.tarikh) tarikh, MAX(t2.city) city, MAX(t2.officeNum) officeNum, MAX(t2.provience) provience 
FROM read_barcodetolid t1 join serial_barcode t2 on t1.ordernum=t2.ordernum 
WHERE (ordernum IS NOT NULL) 
GROUP BY t1.ordernum 
ORDER BY MAX(t1.tarikh) DESC