CODEWITHSUNDEEP
sqlsqlite
Eliezer
Eliezer

Reputation: 7357

Sqlite NOT IN Syntax

I'm doing an audit of one of my Android apps, and I noticed something peculiar.

I have a list of IDs, and I want to remove all rows from a table that don't have an _id in that list.

I would think the correct syntax be:

DELETE FROM table WHERE _id NOT IN...

However, my code has:

DELETE FROM table WHERE NOT _id IN...

Are these equivalent, or will the second statement do something unexpected?

Upvotes: 2

Views: 42

Answers (1)

Giorgi Nakeuri
Giorgi Nakeuri

Reputation: 35790

Basics of boolean algebra https://en.m.wikipedia.org/wiki/De_Morgan%27s_laws

id in(x1,x2,...xn) means
id = x1 or id = x2 or ... id = xn

id not in(x1,x2,...xn) means
id <> x1 and id <> x2 and ... id <> xn

not id in(x1,x2,...xn) means
not(id = x1 or id = x2 or ... id = xn) that means
not(id = x1) and not(id = x2) and ... not(id = xn) that means
id <> x1 and id <> x2 and ... id <> xn

So they are the same.

Upvotes: 2

Related Questions