[Resolved] back to basics...

[zzz]

If I LEFT JOIN additional tables, do I need to also add them where I indicate what to select

SELECT * FROM T1
LEFT JOIN T2 ON ( T1.id = T2.id ) 

Will this automatically select everything from T2 as well?

[sfullman]

yes it will select all from both tables.

If you minimize what you select, you usually get a faster response, so if you just wanted to get from one table, do this:

SELECT T1.*, T2.field1, T2.field2
FROM
T1 LEFT JOIN T2 ON ...

FYI you can left join a table on itself in certain cases, so in this case you would give each instance a name:

SELECT
donors., sponsors.
FROM
T1 donors LEFT JOIN T1 sponsors ON
donors.parent_id = sponsors.id

WHERE sponsors.id IS NOT NULL

This would get you all donors with a sponsor (where donors and sponsors are both records in the same table).

HTH
Sam

[zzz]

Wow! Thanks. After closer look I've found an erro in my code that was causing grief.

But talking about speeding up response... I've come accross caching examples in the manual. Is it something worth looking at? I select partial results from a large table based on a particular var, would that prevent caching?

I'd sure love you to take a look at my other desperate cries for help on this board.

😉