Record IDs: 15 vs 18 Characters
By the end of this lesson, you'll be able to:
- Explain the difference between the 15-character and 18-character forms of a Salesforce Id
- Recognize why Apex always uses the 18-character form for comparisons
- Understand what makes the 18th-character suffix unique to the 18-character form
Prerequisites: "Relationships in Apex"
Two formats, same record
15-character: 001XX000003DHP0
18-character: 001XX000003DHP0YAOBoth refer to the exact same Account record. The 15-character form is what a user sees in the browser's URL bar; the 18-character form is what the API (and Apex) always uses internally.
Why the 15-character form is risky
The 15-character Id is case-sensitive — 001XX000003DHP0 and 001xx000003dhp0 would be treated as different Ids, even though a careless copy-paste or a case-insensitive system (like a spreadsheet or some databases) could easily mix up the casing. This makes it a poor choice for programmatic comparison.
The extra 3 characters solve this
Id recordId = '001XX000003DHP0YAO'; // 18 charactersThe 18-character form appends 3 extra characters that encode the case of the original 15 characters — making the full 18-character Id case-insensitive for comparison purposes. This is exactly why Apex's Id type and every SOQL query always deal in the 18-character form: it removes an entire category of "these look equal but technically aren't" bugs.
Exercise
As a comment, explain why comparing two 15-character Ids with == could produce a wrong result even when they refer to the same record.
Show hint
Think about case sensitivity.
Record IDs: 15 vs 18 Characters Quiz
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Summary
Every Salesforce record has two valid Id formats — a 15-character case-sensitive one and an 18-character case-insensitive one — and Apex always works with the 18-character form to avoid a subtle class of bugs.