Your First SOQL Query
By the end of this lesson, you'll be able to:
- Write a SOQL query selecting specific fields
- Assign a single-record query result directly to a variable of that type
- Explain why selecting only needed fields matters
Prerequisites: "What Is SOQL?"
The basic shape
List<Contact> contacts = [SELECT Id, FirstName, LastName, Email FROM Contact];SELECT lists exactly which fields to retrieve; FROM names the object. Only the fields listed here are populated on each returned record — trying to read a field you didn't select throws a runtime error, reinforcing the habit of listing every field you'll actually use.
Assigning a single-record result directly
Account acc = [SELECT Id, Name FROM Account WHERE Name = 'Acme Logistics' LIMIT 1];
System.debug(acc.Name);When you know a query returns exactly one record (often paired with LIMIT 1, covered soon), you can assign it directly to a single Account variable instead of a List<Account> — but if the query actually returns zero or more than one record, this throws a runtime exception, so it's only safe when you're certain of the count.
Why selecting only needed fields matters
// Wasteful: selects every field on the object
List<Account> accounts = [SELECT FIELDS(ALL) FROM Account LIMIT 10];
// Better: select only what this code actually uses
List<Account> accounts = [SELECT Id, Name, Industry FROM Account LIMIT 10];Selecting unused fields costs real query performance and makes the intent of the query less clear to a reader — exactly the "read it out loud" clarity habit from Module 14, applied to SOQL: a query's SELECT clause should read like a list of exactly what the code below actually needs.
Exercise
Write a SOQL query that selects Id, Name, and Industry from Account where the Name is 'Acme Logistics', limited to 1 result, assigned directly to a single Account variable.
Show hint
Account acc = [SELECT ... WHERE Name = 'Acme Logistics' LIMIT 1];
Your First SOQL Query Quiz
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Summary
A basic SOQL query names the fields you want and the object to query them from — the SELECT and FROM clauses form the backbone of every query you'll ever write.