SQL：如何将其转换为一个查询？

Question

UPDATE a
    SET CountOfAA=dt.CountOf
    FROM @MediaResurce  a
        INNER JOIN (SELECT 
                        aa.Sku,ISNULL(COUNT(bb.sku),0) AS CountOf
                        FROM @MediaResurce                      aa
                            LEFT OUTER JOIN @MediaResurce_Pics  bb 
                            ON aa.sku=bb.sku
                        WHERE somecol = 0
                        GROUP BY aa.Sku
                   ) dt ON a.sku=dt.sku

/////////////

UPDATE a
    SET CountOfBB=dt.CountOf
    FROM @MediaResurce  a
        INNER JOIN (SELECT 
                        aa.Sku,ISNULL(COUNT(bb.sku),0) AS CountOf
                        FROM @MediaResurce                      aa
                            LEFT OUTER JOIN @MediaResurce_Pics  bb 
                            ON aa.sku=bb.sku
                         WHERE somecol = 1
                        GROUP BY aa.Sku
                   ) dt ON a.sku=dt.sku

Answer 1

This should be what you are looking for:

UPDATE a
SET 
  CountOfAA = dt.CountOfAA,
  CountOfBB = dt.CountOfBB
FROM @MediaResurce  a
INNER JOIN (
  SELECT
    SUM(
      case somecol 
        when 0 then 1
        else 0
      end
    ) AS CountOfAA,
    SUM(
      case somecol 
        when 1 then 1
        else 0
      end
    ) AS CountOfBB
    FROM @MediaResurce aa
    LEFT OUTER JOIN @MediaResurce_Pics bb 
      ON aa.sku=bb.sku
) dt ON a.sku=dt.sku

Instead of two separate queries to count each instance, you can SUM "1" or "0" based on the requirements of your "somecol".

Answer 2

Well you can easily do it as

UPDATE a
SET CountOfAA=dt.CountOf,
    CountOfBB=dt2.CountOf
FROM @MediaResurce  a
    INNER JOIN (SELECT 
                    aa.Sku,ISNULL(COUNT(bb.sku),0) AS CountOf
                    FROM @MediaResurce                      aa
                        LEFT OUTER JOIN @MediaResurce_Pics  bb 
                        ON aa.sku=bb.sku
                    WHERE somecol = 0
                    GROUP BY aa.Sku
               ) dt ON a.sku=dt.sku
    INNER JOIN (SELECT 
                    aa.Sku,ISNULL(COUNT(bb.sku),0) AS CountOf
                    FROM @MediaResurce                      aa
                        LEFT OUTER JOIN @MediaResurce_Pics  bb 
                        ON aa.sku=bb.sku
                     WHERE somecol = 1
                    GROUP BY aa.Sku
               ) dt2 ON a.sku=dt2.sku

Which is the lazy and inneficient way, another method might be something like this:

SUM(somecol) AS 'count where somecol=1'
count(*) - SUM(somecol) AS 'count where somecol=0'
...
where somecol in (0,1) //only need if somecol can be something other than 0 or 1!