如何在日期范围内获取缺失值？

Question

我有以下结构的表：

我试图在两个日期之间获取分组值，问题是，我想重新调整不在选择日期的行，例如我有

的范围

WHERE m.date BETWEEN "2014-09-02" AND "2014-09-10"

但是例如在2014-09-06日期表中没有相关的行，所以结果应该是

 2014-09-06| 0 | 0 | 0 | 0

我该怎么办？ （如果可以使用SQLLite数据库）。

以下是我使用的查询：

  SELECT substr(m.date, 1, 10) as my_date, COUNT(m.ID) AS 'NUMBER_OF_ALL_CALLS',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'DONE'
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_DONE',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'NOT_INTERESTED' 
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_NOT_INTERESTED',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'NO_APPOINTMENT'
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_NO_APP'
    FROM dialed_calls m
    WHERE m.date BETWEEN "2014-09-02" AND "2014-09-05"
    GROUP BY my_date

非常感谢您的帮助。

表格结构：

BEGIN TRANSACTION;

CREATE TABLE dialed_calls(Id integer PRIMARY KEY,
'date' datetime,
'called_number' VARCHAR(45),
'call_result' VARCHAR(45),
'call_duration' INT,
'synced' BOOL);

/* Create few records in this table */
INSERT INTO dialed_calls VALUES(1,'2014-09-02 15:54:34+0200',
'800123456', 'NOT_INTERESTED', 10, 0);
INSERT INTO dialed_calls VALUES(2,'2014-09-02 15:56:30+0200',
'800123456', 'NO_APPOINTMENT', 10, 0);
INSERT INTO dialed_calls VALUES(3,'2014-09-02 16:01:49+0200',
'800123456', 'DONE', 9, 0);
INSERT INTO dialed_calls VALUES(4,'2014-09-02 16:03:03+0200',
'800123456', 'NO_APPOINTMENT', 69, 0);
INSERT INTO dialed_calls VALUES(5,'2014-09-02 18:09:34+0200',
'800123456', 'NO_APPOINTMENT', 3, 0);
INSERT INTO dialed_calls VALUES(6,'2014-09-02 18:54:02+0200',
'123456789', 'NO_APPOINTMENT', 89, 0);
INSERT INTO dialed_calls VALUES(7,'2014-09-02 18:55:25+0200',
'123456789', 'NOT_INTERESTED', 89, 0);
INSERT INTO dialed_calls VALUES(8,'2014-09-03 18:36:58+0200',
'123456789', 'DONE', 185, 0);
INSERT INTO dialed_calls VALUES(9,'2014-09-04 18:36:58+0200',
'123456789', 'DONE', 185, 0);
INSERT INTO dialed_calls VALUES(10,'2014-09-05 18:36:58+0200',
'123456789', 'DONE', 185, 0);
COMMIT;

Answer 1

这是加入Calendar表的好例子。

http://web.archive.org/web/20070611150639/http://sqlserver2000.databases.aspfaq.com/why-should-i-consider-using-an-auxiliary-calendar-table.html 请注意，这是一个SQL Server链接，但您可以将其调整为SQLlite。

您可以进行计算，然后将结果右键连接到日历表，以便日期显示为NULL值。或者你可以将空值COALESCE（）更有意义，比如0。

Answer 2

试试这个：

SELECT 
  d.date AS DATE, 
  IFNULL(NUMBER_OF_ALL_CALLS, 0) AS NUMBER_OF_ALL_CALLS, 
  IFNULL(RESULT_DONE, 0) AS RESULT_DONE, 
  IFNULL(RESULT_NOT_INTERESTED, 0) AS RESULT_NOT_INTERESTED, 
  IFNULL(RESULT_NO_APP, 0) AS RESULT_NO_APP
FROM 
 (SELECT DATE('1970-01-01', '+' || (t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) || ' days') 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) d
LEFT JOIN 
(
    SELECT substr(m.date, 1, 10) as my_date, COUNT(m.ID) AS 'NUMBER_OF_ALL_CALLS',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'DONE'
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_DONE',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'NOT_INTERESTED' 
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_NOT_INTERESTED',
    (SELECT COUNT(*) FROM dialed_calls subq WHERE subq.call_result = 'NO_APPOINTMENT'
    AND substr(m.date, 1, 10) = substr(subq.DATE, 1, 10)) as 'RESULT_NO_APP'
    FROM dialed_calls m
    GROUP BY my_date
) t
ON d.date = t.my_date
WHERE d.date BETWEEN '2014-09-02' AND '2014-09-10'
ORDER BY d.date;

上述查询将首先检索指定日期范围之间的日期，然后将检索到的值与您的表格连接。

Answer 3

要获得中间日期作为查询结果，您需要一个包含范围内所有日期的表。 在某些rdbms中，您可以填充临时表以加入。 你必须只比较日期部分（没有时间）。

小心你的中间因为第二个日期的时间是00:00:00，也许它不是你的意思。