【问题标题】：how to use ROW_NUMBER of T-SQL in SQLite with group by query?如何在 SQLite 中将 T-SQL 的 ROW_NUMBER 与 group by 查询一起使用？
【发布时间】：2013-10-18 08:38:23
【问题描述】：

我已经检查过了：How to use ROW_NUMBER in sqlite

但这对我没有帮助。我已经这样查询了，它返回了错误的行索引。查询有什么问题？

SELECT (select count(*) from medicalrecords b where a.id >= b.id ) as cnt,avg(bmi)
FROM MedicalRecords a 
WHERE Date BETWEEN datetime('now', '-1 month') AND datetime('now', 'localtime') 
group by strftime('%W', Date)

SQL Fiddle

【问题讨论】：

“假行索引”是什么意思？你期待什么，你得到了什么？
我期望 1、2、3，...，但我得到的不是这些值，而是一些随机数。
我添加了SQL Fiddle

标签： sql sqlite

【解决方案1】：

这可以在单个查询中完成，但使用VIEW 会变得更容易：

-- Groups (without sequencial):
CREATE VIEW Grp0 AS SELECT DISTINCT STRFTIME('%W', Date) AS Week FROM MedicalRecords WHERE Date BETWEEN DATETIME('NOW', '-1 month') AND DATETIME('now', 'localtime');

-- Groups (with sequencial):
CREATE VIEW Grp AS SELECT (SELECT COUNT() FROM Grp0 AS _ WHERE Week<=Grp0.Week), Week FROM Grp0;

-- Query:
SELECT Week, (SELECT AVG(bmi) FROM MedicalRecords WHERE STRFTIME('%W', Date) = Week)) FROM Grp;

【讨论】：