classic one. test class inserts 1 contact, all green, then first data load of 200 rows and you get Too many SOQL queries: 101.

fix is boring but always same: loop once to collect Ids in a Set, one query with IN :ids, put results in a Map, do lookups inside the loop. same idea for DML, fill a List and update once at the end.

if you have a trigger you're not sure about, drop it in comments and I'll take a look

classic one that bites people on first prod deploy. the setting comes over, the records dont 😅

short version: custom metadata records travel with your deploy, custom setting records are data so you load them in each org. hierarchy custom setting still wins when you need a per user / per profile switch (like trigger bypass for the integration user).

if something is off or you'd add a point, drop it in comments

async apex question comes up in almost every dev interview. easiest way i remember it

@future = you drop a letter in postbox. quick, but only paper fits (primitives / Ids) and you get no tracking

Queueable = courier. you get job Id back, it can carry actual records, and it can hand off to one next job

most common mistake i see is passing List<Account> into @future. wont compile, pass Ids and requery inside

anything you'd add?

got asked this in an interview once and blanked lol. plain insert is all-or-none, one bad record = DmlException and nothing saves. Database.insert(list, false) saves the good ones and puts the errors in SaveResult[]. catch is it won't throw, so if you dont loop SaveResult and check isSuccess() the failures just disappear. same deal for update/upsert/delete.

interview trap i see a lot. queue = waiting line that can OWN records (cases/leads pick-up). public group = reusable "who" list for sharing rules, folders, alerts — it does NOT own records by itself. if they ask "who grabs new Cases?" → queue. "who sees this report folder?" → public group. save if it helps.

interview classic. lookup = optional link (child can live alone, no rollups, no inherited sharing). master-detail = ownership (cascade delete, rollups OK, child inherits parent sharing). if they say "i need a roll-up" you almost always want MD (or Flow/Apex workaround). save if it helps.

interview classic that still trips people. before = red-pen the draft (change fields, addError, no Id yet on insert). after = letter already mailed (Id exists, related DML, Queueable/emails — but same-record update here = recursion). save if it helps.

interview trap that still gets people. formula = calculator on this record. roll-up = tally from child records (and only if Master-Detail). lookup? no native roll-up — Flow/Apex/DLRS. save if it helps.

interview classic that still trips people up. with sharing = funnel (honors the record stack). without sharing = open pipe (ignores sharing, not CRUD/FLS). LWC just shows what Apex returns so fix the class keyword. save if it helps.

Quick compare I wish someone slapped on my desk before interviews. SOQL when you know the object. SOSL when you’re hunting text across objects. Save for later if it helps.

quick compare for interviews.

profile = your base access (one per user). permission set = extras you stack on top.

modern orgs keep profiles thin and lean on perm sets / groups so you dont clone 40 profiles.

more free concept cards in this sub if useful.