Salesforce

-- Every field must be named. There is no SELECT *. SELECT Id, Name, StageName, Amount, CloseDate FROM Opportunity WHERE StageName = 'Closed Won' AND CloseDate = THIS_QUARTER ORDER BY Amount DESC LIMIT 100 -- Parent traversal: dot-walk UP through a lookup (max 5 levels) SELECT Id, Name, Account.Name, Account.Owner.Email FROM Contact WHERE Account.Industry = 'Technology' -- Child subquery: traverse DOWN using the relationship name (max 1 level) SELECT Id, Name, (SELECT Id, Subject, Status FROM Cases WHERE Status != 'Closed') FROM Account WHERE BillingCountry = 'United Kingdom' -- Custom relationships use __r for the relationship, __c for the field SELECT Id, Custom_Field__c, Parent_Object__r.Name FROM My_Object__c -- Date literals — use these rather than hardcoded dates WHERE CreatedDate = LAST_N_DAYS:30 WHERE CloseDate = THIS_FISCAL_QUARTER WHERE LastModifiedDate = YESTERDAY -- Aggregates. Anything not aggregated must be in GROUP BY. SELECT StageName, COUNT(Id) total, SUM(Amount) value FROM Opportunity GROUP BY StageName HAVING SUM(Amount) > 100000 -- Semi-join / anti-join SELECT Id FROM Account WHERE Id IN (SELECT AccountId FROM Opportunity) SELECT Id FROM Account WHERE Id NOT IN (SELECT AccountId FROM Case) -- Recover deleted records (within the ~15-day recycle bin window) SELECT Id, Name FROM Account WHERE IsDeleted = true ALL ROWS -- FOR UPDATE locks rows for the transaction SELECT Id FROM Account WHERE Id = :accId FOR UPDATE -- SOSL: text search ACROSS objects, which SOQL cannot do FIND {Acme*} IN ALL FIELDS RETURNING Account(Id, Name), Contact(Id, Name, Email), Lead(Id, Company)

// WRONG — a query and a DML inside a loop. // 200 records = 200 queries = limit exceeded, transaction fails. for (Account a : Trigger.new) { List<Contact> cs = [SELECT Id FROM Contact WHERE AccountId = :a.Id]; for (Contact c : cs) { c.Description = 'x'; update c; } } // RIGHT — one query, one DML, regardless of batch size. Set<Id> accountIds = Trigger.newMap.keySet(); List<Contact> toUpdate = new List<Contact>(); for (Contact c : [SELECT Id, AccountId FROM Contact WHERE AccountId IN :accountIds WITH USER_MODE]) { c.Description = 'x'; toUpdate.add(c); } if (!toUpdate.isEmpty()) { update toUpdate; } // One trigger per object, delegating to a handler class. trigger AccountTrigger on Account (before insert, before update, after insert, after update) { new AccountTriggerHandler().run(); } // Partial success — process what you can, collect the failures. Database.SaveResult[] results = Database.update(toUpdate, false); for (Database.SaveResult r : results) { if (!r.isSuccess()) { System.debug(r.getErrors()[0].getMessage()); } }