SF2-教义DQL-选择几列

Question

I have a table Item with the following columns:

• Id
• Category
• value
• date

I build a SQL request which returns all the lines with the latest date for each category:

SELECT *
FROM item i
WHERE (i.category, i.date) IN (SELECT category, MAX(date)
                               FROM item
                               GROUP BY category)

This works fine and returns what I need.

I work with Symfony2 and Doctrine, so I would prefer to use DQL (or even better: the QueryBuilder) instead of NativeSQL.

So here is my DQL request :

SELECT i
FROM MyBundle:Item i
WHERE (i.category, i.date) IN (SELECT i2.category, MAX(i2.date) 
                               FROM MyBundle:Item i2
                               GROUP BY i2.category
                               )

Which gives me the error:

QueryException: [Syntax Error] line 0, col 103: Error: Expected Doctrine\ORM\Query\Lexer::T_CLOSE_PARENTHESIS, got ','

If I remove the first couple of parenthesis, I get :

QueryException: [Syntax Error] line 0, col 102: Error: Expected =, <, <=, <>, >, >=, !=, got ','

I thought there was a problem with the WHERE so I tried the following just to see what would happen:

SELECT i
FROM MyBundle:Item i
WHERE i IN (SELECT i2.category, MAX(i2.date) 
            FROM MyBundle:Item i2
            GROUP BY i2.category
            )

I get:

QueryException: [Syntax Error] line 0, col 116: Error: Expected Doctrine\ORM\Query\Lexer::T_FROM, got ','  

But in the doctrine doc, there is an example with several columns after the SELECT, using this same syntax!

Do you have any idea where does my problem come from? Thank you! Regards,

Answer 1

You will need to separate the query's conditional statements; This is because DQL is unable to parse the comma separated field names (i.category, i.date) .

SELECT 
  i 
FROM 
  MyBundle:Item i 
WHERE
  i.category IN ( (SELECT i2.category FROM MyBundle:Item i2 GROUP BY i2.specy) )
AND
  i.date IN ( (SELECT MAX(i2.date) FROM MyBundle:Item i2 GROUP BY i2.specy) )

I would also recommend using parentheses () to wrap any sub queries.

Answer 2

You could use exists :

SELECT 
  i 
FROM 
  MyBundle:Item i 
WHERE
  EXISTS (
    SELECT i2 
    FROM MyBundle:Item i2
    WHERE i2.category = i.category
    GROUP BY i2.category
    HAVING MAX(i2.date) = i.date
  )