Sql 带有join的select语句中的额外重复记录

我有两张表，“read_barcodetolid”和“serial_barcode”。它们都有相同的ordernum字段。我想选择行，不想有重复的值， 首先，我使用了以下查询：

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

它只适用于ordernum字段。但当我加上另一个领域，如城市，。。。它做了一些重复的记录

然后我写了这个：

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

它返回结果，但最后显示一些空记录，当我使用“where ordernum IS NOT NULL”时，它不起作用

我能做什么？

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消除额外重复记录的更好方法是什么？

尝试使用GROUPBY子句

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