Re: (multiple join + subqueries) performence

[Peter Brawley]

Sorry, on the data you show...

+-----+-----+
| eid | aid |
+-----+-----+
| X   | a   |
| X   | b   |
| Y   | a   |
| Z   | b   |
| T   | a   |
| U   | a   |
+-----+-----+

I do not understand how your spec, "list ... eid that share the same aid as (eid='X' and eid='Y') or same as (eid='X') or same as (eid='Y'), as well as the number of aid that they share", could generate row 3 in the desired result you show:

| eid1 | eid2 | eid3 | count(aid)
| X    | Y    | T    | 1
| X    | Y    | U    | 1
| X    |      | Z    | 1

BTW, your data & result displays are more readable if you surround them with [ code ] [ /code ] tags (without the spaces).

PB
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