How to group mysql rows with same column value into one row?

问题

I have two tables, keywords and data.

Table keywords have 2 columns (id, keyword), table data have 3 columns (id[foreign key of keywords.id], name, value).

I am using this query:

SELECT k.id, d.value, d.name
FROM keywords AS k
INNER JOIN data as d ON k.id = d.id

it returns something like:

1 123 name1
1 456 name2
2 943 name1
3 542 name1
3 532 name2
3 682 name3

Each id can have values from 0 to 3 (maybe more in the future).

How can I retrieve all the rows with the same id in the same row?

Like

1 123 456
2 943
3 542 532 682

I want to do this because I want to be able to sort the values.

回答1:

Use GROUP_CONCAT() like this:

 SELECT k.id, GROUP_CONCAT(d.value)
  FROM keywords AS k
  INNER JOIN data as d ON k.id = d.id
  GROUP BY k.id

Also, you may need to do ORDER BY d.name to get exact order of values as you want. Like this:

 SELECT k.id, GROUP_CONCAT(d.value ORDER BY d.name separator ' ')
  FROM keywords AS k
  INNER JOIN data as d ON k.id = d.id
  GROUP BY k.id

来源：https://stackoverflow.com/questions/3664393/how-to-group-mysql-rows-with-same-column-value-into-one-row