存在しないデータに対して空の行を返す

次のようなことができます：

# table creation:

drop table if exists test_table;

create table test_table (your_date date, your_value int(11));
insert into test_table (your_date, your_value) values ('2020-01-01', 1);
insert into test_table (your_date, your_value) values ('2020-01-01', 2);
insert into test_table (your_date, your_value) values ('2020-01-03', 2);
insert into test_table (your_date, your_value) values ('2020-01-07', 3);
insert into test_table (your_date, your_value) values ('2020-01-08', 4);
insert into test_table (your_date, your_value) values ('2020-01-08', 1);

これにより、基本的にすべての日付のリストが作成されます。次に、興味のある日付をフィルタリングし、テーブルとグループに参加します。

whereステートメントの日付をサブクエリ（テーブルの最小および最大の日付）に置き換えて、動的にすることもできます

少し回避策ですが、機能します。

select sbqry.base_date, sum(ifnull(t.your_value, 0))
from (select adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) base_date from
    (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t0,
    (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t1,
    (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t2,
    (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t3,
    (select 0 i union select 1 union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9) t4) sbqry
left join test_table t on base_date = t.your_date
where sbqry.base_date between '2020-01-01' and '2020-01-08'
group by sbqry.base_date;

入力：

+------------+------------+
| your_date  | your_value |
+------------+------------+
| 2020-01-01 |          1 |
| 2020-01-01 |          2 |
| 2020-01-03 |          2 |
| 2020-01-07 |          3 |
| 2020-01-08 |          4 |
| 2020-01-08 |          1 |
+------------+------------+

出力：

+------------+------------------------------+
| base_date  | sum(ifnull(t.your_value, 0)) |
+------------+------------------------------+
| 2020-01-01 |                            3 |
| 2020-01-02 |                            0 |
| 2020-01-03 |                            2 |
| 2020-01-04 |                            0 |
| 2020-01-05 |                            0 |
| 2020-01-06 |                            0 |
| 2020-01-07 |                            3 |
| 2020-01-08 |                            5 |
+------------+------------------------------+