包括SQL查询输出中没有值的行

Question

在我的SQL SERVER 2016数据库中运行以下查询：

SELECT
    u.idnumber,
    gi.idnumber AS code,
    gg.finalgrade AS grade
FROM
    grades AS gg 
INNER JOIN grade_items AS gi ON gg.itemid = gi.id 
INNER JOIN users AS u ON gg.userid = u.id
WHERE gi.idnumber IN ('436','434','313','002','135')
AND (u.idnumber = 'JohnBrown-xyz123);

给了我这个结果：

-------------------------
idnumber    code    grade
-------------------------
John12558   313     96
John12558   135     83

如何为所有5个gi.idnumber包含一行，包括没有成绩的行？

-------------------------
idnumber    code    grade
-------------------------
John12558   436
John12558   434
John12558   313     96
John12558   002
John12558   135     83

数据库表：

用户

id PK

grade_items

id PK

grade_grades

grade_grades.itemid FK（grade_items）

grade_grades.userid FK（用户）

Answer 1

您可以使用value构造：

select tt.idnumber, 
       t.idnumber AS code, 
       tt.grade 
from (values ('436'), ('434'), ('313'), ('002'), ('135')) t (idnumber) 
left join (select
                 u.idnumber,
                 gi.idnumber AS code,
                 gg.finalgrade AS grade
           from grades AS gg 
           inner join grade_items AS gi ON gg.itemid = gi.id 
           inner join users AS u ON gg.userid = u.id
           where u.idnumber = 'JohnBrown-xyz123') tt on left(tt.code, 3) = t.idnumber

如果 idnumber 具有数字类型，则您无需使用' '。

Answer 2

假设＆＃34;没有价值＆＃34;是NULL然后只需在您的WHERE添加一个额外条款：

WHERE (LEFT(gi.idnumber, 3) IN ('436','434','313','002','135')
   OR gi.idnumber IS NULL)

编辑：很明显，上面的内容不起作用，这意味着＆＃34;没有价值＆＃34;并不意味着NULL。相反，你可以尝试：

    WHERE (LEFT(gi.idnumber, 3) IN ('436','434','313','002','135','')

如果这不起作用，请提供消耗品样本数据，我们可以对其进行测试：Forum Etiquette: How to post data for a T-SQL Question

Answer 3

您需要cross join才能看到所需内容：

select 
    u.idnumber,
    gi.idnumber code,
    ISNULL(gg.finalgrade, 0) grade
from  users u
    cross join grade_items gi
    left outer join grades gg on gg.itemid = gi.id  and gg.userid = u.id
where gi.idnumber in ('436','434','313','002','135')
    and u.idnumber = 'JohnBrown-xyz123'

finalgrade中的

空值不能替换为'N / A'，因为它们是数字，而不是字符串，我将它们替换为零。