我正在使用以下数据库:
CREATE TABLE datas (d_id INTEGER PRIMARY KEY, name_id numeric, countdata numeric);
INSERT INTO datas VALUES(1,1,20); //(NULL,1,20);
INSERT INTO datas VALUES(2,1,47); //(NULL,1,47);
INSERT INTO datas VALUES(3,2,36); //(NULL,2,36);
INSERT INTO datas VALUES(4,2,58); //(NULL,2,58);
INSERT INTO datas VALUES(5,2,87); //(NULL,2,87);
CREATE TABLE names (n_id INTEGER PRIMARY KEY, name text);
INSERT INTO names VALUES(1,'nameA'); //(NULL,'nameA');
INSERT INTO names VALUES(2,'nameB'); //(NULL,'nameB');
我想要做的是选择names
- 的所有值(行)的所有列datas
将被附加到其中的行 where datas
。countdata
是最大的n_id
(当然,在哪里name_id = n_id
)。
我可以通过以下查询到达那里:
sqlite> .header ON
sqlite> SELECT * FROM names AS n1
LEFT OUTER JOIN (
SELECT d_id, name_id, countdata FROM datas AS d1
WHERE d1.countdata IN (
SELECT MAX(countdata) FROM datas
WHERE name_id=1
)
) AS p1 ON n_id=name_id;
n1.n_id|n1.name|p1.d_id|p1.name_id|p1.countdata
1|nameA|2|1|47
2|nameB|||
...但是 - 显然 - 它仅适用于单行(由 明确设置的行name_id=1
)。
问题是,每当我尝试以某种方式引用“当前”时,SQL 查询都会失败n_id
:
sqlite> SELECT * FROM names AS n1
LEFT OUTER JOIN (
SELECT d_id, name_id, countdata FROM datas AS d1
WHERE d1.countdata IN (
SELECT MAX(countdata) FROM datas
WHERE name_id=n1.n_id
)
) AS p1 ON n_id=name_id;
SQL error: no such column: n1.n_id
有什么方法可以在 Sqlite2 中实现我想要的吗?
提前致谢,
干杯!