Apex Developer Guide

Apex Developer Guide
Release Notes
Getting Started with Apex
Writing Apex
Data Types and Variables
Control Flow Statements
Classes, Objects, and Interfaces
Working with Data in Apex
Working with sObjects
Data Manipulation Language
How DML Works
Adding and Retrieving Data With DML
DML Statements vs. Database Class Methods
DML Operations As Atomic Transactions
DML Operations
Exception Handling
More About DML
Locking Records
Locking Statements
Locking in a SOQL For Loop
Avoiding Deadlocks
SOQL and SOSL Queries
SOQL For Loops
sObject Collections
Dynamic Apex
Apex Security and Sharing
Custom Settings
Document Your Apex Code
Running Apex
Debugging, Testing, and Deploying Apex
Apex Reference
Appendices
PDF

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Locking in a SOQL For Loop

The FOR UPDATE keywords can also be used within SOQL for loops. For example:
1for (Account[] accts : [SELECT Id FROM Account
2                        FOR UPDATE]) {
3    // Your code
4}

As discussed in SOQL For Loops, the example above corresponds internally to calls to the query() and queryMore() methods in the SOAP API.

Note that there is no commit statement. If your Apex trigger completes successfully, any database changes are automatically committed. If your Apex trigger does not complete successfully, any changes made to the database are rolled back.