Question

I can produce the same result with the where clause inside the join or the where clause outside the join, like:

select *
from a
join b on b.id = a.id and b.type = 1

or

select *
from a
join b on b.id = a.id
where
    b.type = 1

Whats better? Why?

ps: feel free to edit my title, i dont know how to proper name the question.

Answer 1

Using the father Sybase ASE 15.0 and with no statistics on both tables:

First query

STEP 1
    The type of query is SELECT.

    FROM TABLE
        b
    Nested iteration.
    Table Scan.
    Forward scan.
    Positioning at start of table.
    Using I/O Size 2 Kbytes for data pages.
    With LRU Buffer Replacement Strategy for data pages.

    FROM TABLE
        a
    Nested iteration.
    Table Scan.
    Forward scan.
    Positioning at start of table.
    Using I/O Size 2 Kbytes for data pages.
    With LRU Buffer Replacement Strategy for data pages.

Second query

STEP 1
    The type of query is SELECT.

    FROM TABLE
        b
    Nested iteration.
    Table Scan.
    Forward scan.
    Positioning at start of table.
    Using I/O Size 2 Kbytes for data pages.
    With LRU Buffer Replacement Strategy for data pages.

    FROM TABLE
        a
    Nested iteration.
    Table Scan.
    Forward scan.
    Positioning at start of table.
    Using I/O Size 2 Kbytes for data pages.
    With LRU Buffer Replacement Strategy for data pages.

Both queries have the same execution plan so they will take the same time 🙂