如何使用GROUP BY和WHERE Con​​dition查询UNION

Question

我的 sqlfiddle

我的数据库架构和在线查询

查询1

SELECT pk_video_master_id AS _id,
video_title AS title1,
COUNT(fk_video_master_id) AS sub_title_1,
SUM(video_detail_length) AS sub_title_2,
-1007 AS module 
FROM tbl_video_master 
LEFT JOIN tbl_video_detail ON fk_video_master_id = pk_video_master_id 
WHERE title1 LIKE '%a%' GROUP BY _id

查询2

 SELECT pk_surveys_id AS _id ,
 surveys_title AS title1,
 surveys_end_date AS sub_title_1,
 COUNT(fk_survey_detail_survey_id) AS sub_title_2, 
-1006 AS module
 FROM tbl_surveys 
 LEFT JOIN tbl_survey_detail ON fk_survey_detail_survey_id = pk_surveys_id 
 WHERE title1 LIKE '%a%' GROUP BY _id

我想UNION这2个查询我也创建了

SELECT pk_video_master_id AS _id,
video_title AS title1,COUNT(fk_video_master_id) AS sub_title_1,
SUM(video_detail_length) AS sub_title_2,-1007 AS module 
FROM tbl_video_master 
LEFT JOIN tbl_video_detail ON fk_video_master_id = pk_video_master_id 
UNION 
SELECT pk_surveys_id AS _id ,surveys_title AS title1,
surveys_end_date AS sub_title_1,
COUNT(fk_survey_detail_survey_id) AS sub_title_2, 
-1006 AS module
FROM tbl_surveys 
LEFT JOIN tbl_survey_detail ON fk_survey_detail_survey_id = pk_surveys_id 
WHERE title1 LIKE '%a%' GROUP BY module

但它只返回2条记录

我的欲望输出是在表TITLE1字段

中搜索

所以请帮帮我

Answer 1

您从query1中删除了GROUP BY。大多数其他DBMS会引发错误，但SQLite只返回一条带有随机信息的记录。顺便说一下，你也删除了WHERE子句。

将完整的查询1粘贴到完整的查询中2.并使用UNION ALL而不是UNION，因为无论如何都不会删除重复项。

SELECT pk_video_master_id AS _id,
video_title AS title1,COUNT(fk_video_master_id) AS sub_title_1,
SUM(video_detail_length) AS sub_title_2,-1007 AS module 
FROM tbl_video_master 
LEFT JOIN tbl_video_detail ON fk_video_master_id = pk_video_master_id 
WHERE title1 LIKE '%a%' GROUP BY _id
UNION ALL
SELECT pk_surveys_id AS _id ,surveys_title AS title1,
surveys_end_date AS sub_title_1,
COUNT(fk_survey_detail_survey_id) AS sub_title_2, 
-1006 AS module
FROM tbl_surveys 
LEFT JOIN tbl_survey_detail ON fk_survey_detail_survey_id = pk_surveys_id 
WHERE title1 LIKE '%a%' GROUP BY module;

以下是您的SQL文件：http://sqlfiddle.com/#!5/03ecc/14。