Question

I have two tables:

ab_message

• user_id
• title
• content
• question

and ab_message_rating:

• id
• user_id
• message_id
• created_at
• updated_at

ab_message is in a OneToMany Relation with ab_message_rating. Every Entry in ab_message_rating has 1, 2 or 3 as rating value.

So i want to select in one query the Message an all related Tables Entries. The Key is, that i need in this query rating to be counted BY value.

For Example the Result schuld be:

Message abc has 5 entries of rating 1, 7 entries of rating 2, and 10
entries of rating 3

how to do that in a query? Something like Group By and A Join?

Answer 1

SELECT ID, Title, Content, 
        MAX(CASE WHEN Rating = 'Rating 1' THEN totalCount ELSE NULL END) 'Rating 1',
        MAX(CASE WHEN Rating = 'Rating 2' THEN totalCount ELSE NULL END) 'Rating 2',
        MAX(CASE WHEN Rating = 'Rating 3' THEN totalCount ELSE NULL END) 'Rating 3'
FROM    
(
    SELECT  a.ID, a.Title, a.Content,
            b.Rating, COUNT(*) totalCount
    FROM    Message a
            LEFT JOIN Rating b
                ON a.ID = b.MessageID
    GROUP BY a.ID, a.Title, a.Content, b.Rating
) r
GROUP BY ID, Title, Content

Sample Result:

╔════╦═══════════════╦══════════╦══════════╦══════════╦══════════╗
║ ID ║     TITLE     ║ CONTENT  ║ RATING 1 ║ RATING 2 ║ RATING 3 ║
╠════╬═══════════════╬══════════╬══════════╬══════════╬══════════╣
║  1 ║ Lost Prophets ║ CONTENT1 ║        1 ║        5 ║        7 ║
║  2 ║ Cannibal      ║ CONTENT2 ║        3 ║        4 ║        6 ║
║  3 ║ Sigbin        ║ CONTENT3 ║        4 ║        4 ║        1 ║
╚════╩═══════════════╩══════════╩══════════╩══════════╩══════════╝