WestKeys
Programming Phoenix 1.4, Writing Queries with Keyword Syntax
In Chapter 7 - Diving Deeper into Ecto Queries - Writing Queries with Keyword Syntax, we have:
Repo.one from u in User,
select: count(u.id),
where: ilike(u.username, "j%") or
ilike(u.username, "c%")
Is there any reason in particular we are using count(u.id) rather than count(u)?
First Post!
cenotaph
basically 1:1 translation from SQL
When you work with multiple tables you need to shorthand them to specify the table if you don’t want to write the full name every time.
select u.* from users u;
translated here with really useful scopes
edit: let me get into details count(u) would ask to count instances of users table in sql, such statement doesn’t exist in SQL of course.
Last Post!
WestKeys
Not really, why would a db engine load every column in a row to count number of rows in a table? I’d be surprised if count(*) was ever implemented this way
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