Hi all, i have a 3[novice-like] questions:

1
When joining two tables, if joining a table to itself via aliasing, as opposed to joining two separate tables, is this less power/speed/resource intensive or more so?

2
SELECT...
FROM...
WHERE...
AND a.col1 = 'jones' <--- is this line an actual join, or a comparison
operation/condition?

3, are outer joins so much of a burdon (regardless of actual querying)? i.e. are they more performance intensive than triggers per se? Do certain join types such as outerjoins, are more performance deteriorating if VL volumes of data stored in the db as opposed to smaller volumes of data, when querying?

Thanks for reading, looking forward to replies!

1. yes!

2. that's not a join condition

3. you cannot compare outer joins to triggers -- performance of outer joins depends on indexes, not on the number of rows

Hi r937,

Thanks for your help

btw with Q2, as it is not an actual join whats the correct tech term to describe what it is? Is it a comparison operation?

it's a filter condition

at least, that's what i call it

some people call it a single table predicate as opposed to a join predicate

(predicate is a fifty cent word which means condition)

both filter and join conditions involve a comparison operation

p.s. not sure if you understood my answer to your first question

is it less power/speed/resource intensive or more so?

the answer is yes, probably one or the other, unless it's equal

what this means is that the performance depends on indexing and not on whether it's a self join or a join of two tables