Question

我有一个格式如下的表：

title            source              subject   
Bill hits Fred   newspaper 1/1/17    Bill     
Bill hits Fred   newspaper 1/1/17    Fred
Bill hits Fred   newspaper 1/1/17    Violence
Mary likes pie   newspaper 1/4/17    Mary
Mary likes pie   newspaper 1/4/17    Pie 
Mary likes pie   newspaper 1/4/17    Apple
John dies        newspaper 1/4/17    John 
John dies        newspaper 1/4/17    Obituary
...

我需要实现的是一个查询，它查找标题和源字段具有相同值的所有行，并组合成一个连接主题字段的记录。即上述数据的输出为：

title            source              subject   
Bill hits Fred   newspaper 1/1/17    Bill, Fred, Violence     
Mary likes pie   newspaper 1/4/17    Mary, Pie, Apple
John dies        newspaper 1/4/17    John, Obituary
...

我想我需要GROUP_CONCAT但不确定比较所有行的标题和源的确切语法。有点像：

select title, source, GROUP_CONCAT(subject) from mytable
WHERE

??? ＆lt;＆lt; - 不确定如何说出“title = title and source = source”

解决方案：我缺少GROUP BY：

SELECT title, source, GROUP_CONCAT(subject) from mytable GROUP BY title, source

Answer 1

使用：

SELECT title, source, GROUP_CONCAT(subject) from mytable GROUP BY title, source

Answer 2

试试这个

select title,source,group_concat(subject) as subject from tbl5 group by title;

check on fiddle

组合包含两个具有相同值的单独字段的行

2 个答案: