Question

I am looking for an access query, but a sql server 2008 could be sufficient as I can use a passthrough feature in access.

My data looks like this .

--------------------------------------------------------------
id   nameid   name        score         diff          include 
--------------------------------------------------------------
1     0001     SO          100           0                0
2     0001     SO          100           0                0
3     0001     SO          100           0                0
4     0001     SO          100           0                0
5     0001     SO          100           0                0
6     0001     SO          100           0                0

7     0002     MO          10            0                0
8     0002     MO          18            0                1
9     0002     MO          20            0                0
10    0002     MO          14            0                0
11    0002     MO          100           0                0
11    0002     MO          100           0                0

12    0003     MA          10            0                0
13    0003     MA          18            0                1
14    0003     MA          20            0                0
15    0003     MA          14            0                0
16    0003     MA          100           0                1
17    0003     MA          100           0                0

Now what i want is to go through each row and only select the rows where include = 1. THIS IS EASY however ,I don’t want the entire row.. I want to select the “group”. The group can be identified by the nameid (or name).

So for the above I want the following result:

--------------------------------------------------------------
id   nameid   name        score         diff          include 
--------------------------------------------------------------

7     0002     MO          10            0                0
8     0002     MO          18            0                1
9     0002     MO          20            0                0
10    0002     MO          14            0                0
11    0002     MO          100           0                0
11    0002     MO          100           0                0

12    0003     MA          10            0                0
13    0003     MA          18            0                1
14    0003     MA          20            0                0
15    0003     MA          14            0                0
16    0003     MA          100           0                1
17    0003     MA          100           0                0

Answer 1

Ask your table for row with include = 1.

Then join again with the table to have all the rows corresponding to the first query’s nameid :

SELECT DISTINCT m.*
FROM myTable m
    INNER JOIN myTable m2
        ON m.nameid = m2.nameid
        AND m2.include = 1

A join query will work better than an ‘in’ query for big amount of datas. You still need an index on the field ‘nameid’, and on ‘include’ could not hurt too.

An equivalent is with ‘WHERE EXISTS’ :

SELECT m.*
FROM myTable m
WHERE EXISTS
   (
      SELECT * 
      FROM myTable m2
      WHERE m2.include = 1
      AND m2.nameid = m.nameid
   )

You could see the difference here :

Can an INNER JOIN offer better performance than EXISTS

And why you have to use a Where exists when you have a filter with a lot of IDs :

Difference between EXISTS and IN in SQL?