equivalent?

[diggingdeeply]

are these three logically equivalent?

lookup_actions_r.action!=''
NOT lookup_actions_r.action=''
lookup_actions_r.action LIKE '_%'

if so, is one preferable to the other?

[kraada]

Yes they're logically equivalent. The first two end up being run identically in the code so either one of those is going to be preferrable - using LIKE is always slower than using = or !=, therefore if you can use = it's going to be slightly faster. For the most part the speed increase isn't something you're going to notice directly but since they're logically equivalent you might as well use the faster one.