SQL / MYSQL：选择联结表中的所有列

Question

Hi guys i have some question how can i retrieve column data in a junction table properly. for example i have one blog in junction table with many keywords, how can i get the blog including the keywords attached to it.

junction table :

 *junction_table*
  |id| blogID | keywordID|
  |0 | B43    | k12      |
  |0 | B43    | k13      |

let assume that 'B43' blog title is "Hello World!" and 'K12' keyword is 'fun' and 'k31' is 'exciting'. i want to get data as:

  {title: 'Hello World' : keywords: { "fun", "exciting" }

how can i achieve that or is it even possible. thank you

Answer 1

Use GROUP_CONCAT to group the Keyword data

SELECT blogID, GROUP_CONCAT(keywordID) FROM junction_table

If you want the result as like this {title: 'Hello World' : keywords: { "fun", "exciting" }

You can do below

SELECT blogID as `title`, GROUP_CONCAT(keywordID) as `keywords` FROM junction_table

After that, using PHP json_encode(array_here) it will generate as string