[英]MySQL LEFT JOIN with GROUP BY and WHERE IN (sub query)
I have one table with some statistics per date, which I want listed out with MySQL. 我有一个表,每个日期都有一些统计信息,我想用MySQL列出。 For some dates there will be no statistics, so the result should look something like this: 对于某些日期,将没有统计信息,因此结果应如下所示:
2013-03-01: 3 2013-03-01:3
2013-03-02: 2 2013-03-02:2
2013-03-03: 0 2013-03-03:0
2013-03-04: 1 2013-03-04:1
I figured out that filling in the gaps with 0 -zero- could be solved with a separate table with all possible dates and LEFT JOIN. 我发现填充0 -zero-的空隙可以通过一个单独的表来解决,该表包含所有可能的日期和LEFT JOIN。 So far so good. 到现在为止还挺好。
The statistics (impressions) is in the table 'campaigndata': 统计数据(展示次数)位于“Campaigndata”表格中:
id - int(11) date - date campaignid - int(11) impressions - int(11)
But I want to get only some of the statistics. 但我想只得到一些统计数据。 To be more specific, I only want the rows from 'campaigndata' where 'campaignid' is in the table 'campaignfilter' with 'campaigntype' set to 1 (as an example). 更具体地说,我只想要'campaigndata'中的行,其中'campaignid'在表'campaignfilter'中,'campaigntype'设置为1(作为示例)。
This is the table 'campaignfilter': 这是表'campaignfilter':
id - int(11) campaigntype - int(11) campaignid - int(11)
Anyone have clue how this could be done? 任何人都知道如何做到这一点?
PS: The structure of table 'campaigndata' is pretty much locked, since it is based on an automatic import from an external system. PS:表'campaigndata'的结构几乎被锁定,因为它基于从外部系统自动导入。
SAMPLE RECORDS 样本记录
CREATE TABLE demo_campaigndata (
id int(11) NOT NULL AUTO_INCREMENT,
date date NOT NULL,
campaignid int(11) NOT NULL,
impressions int(11) NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO demo_campaigndata (id, date, campaignid, impressions) VALUES
(1, '2013-03-03', 1, 100),
(2, '2013-03-03', 2, 100),
(3, '2013-03-03', 3, 100),
(4, '2013-03-04', 2, 100),
(5, '2013-03-05', 1, 100),
(6, '2013-03-05', 2, 100);
CREATE TABLE demo_campaignfilter (
id int(11) NOT NULL AUTO_INCREMENT,
campaigntype int(11) NOT NULL,
campaignid int(11) NOT NULL,
PRIMARY KEY (id)
);
INSERT INTO demo_campaignfilter (id, campaigntype, campaignid) VALUES
(1, 1, 1),
(2, 1, 3);
CREATE TABLE demo_calendar (
date date NOT NULL,
PRIMARY KEY (date)
);
INSERT INTO demo_calendar (date) VALUES
('2013-03-01'),
('2013-03-02'),
('2013-03-03'),
('2013-03-04'),
('2013-03-05');
DESIRED RESULT 期望的结果
2013-03-01: 0
2013-03-02: 0
2013-03-03: 200
2013-03-04: 0
2013-03-05: 100
SELECT a.date, COUNT(b.campaignid) totalStat
FROM campaigndata a
LEFT JOIN campaignfilter b
ON a.campaignid = b.campaignid AND
b.campaigntype = 1
GROUP BY a.date
To further gain more knowledge about joins, kindly visit the link below: 要进一步了解联接,请访问以下链接:
UPDATE 1 更新1
SELECT a.date,
COALESCE(b.totals,0) totals
FROM demo_calendar a
LEFT JOIN
(
SELECT a.date, SUM(impressions) totals
FROM demo_campaigndata a
INNER JOIN demo_campaignfilter b
ON a.campaignid = b.campaignid
WHERE b.campaigntype = 1
GROUP BY a.date
) b ON a.date = b.date
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