Apex Developer Guide

Getting Started
Writing Apex
Ways to Invoke Apex
Finishing Touches
Reference
Apex DML Operations
ApexPages Namespace
AppLauncher Namespace
Approval Namespace
Auth Namespace
Cache Namespace
Canvas Namespace
ChatterAnswers Namespace
ConnectApi Namespace
Database Namespace
Batchable Interface
BatchableContext Interface
DeletedRecord Class
DeleteResult Class
DMLOptions Class
DmlOptions.AssignmentRuleHeader Class
DMLOptions.DuplicateRuleHeader Class
DmlOptions.EmailHeader Class
DuplicateError Class
EmptyRecycleBinResult Class
Error Class
GetDeletedResult Class
GetUpdatedResult Class
LeadConvert Class
LeadConvertResult Class
MergeResult Class
QueryLocator Class
QueryLocator Methods
QueryLocatorIterator Class
SaveResult Class
UndeleteResult Class
UpsertResult Class
Datacloud Namespace
DataSource Namespace
Dom Namespace
Flow Namespace
KbManagement Namespace
Messaging Namespace
Process Namespace
QuickAction Namespace
Reports Namespace
Schema Namespace
Search Namespace
Site Namespace
Support Namespace
System Namespace
TerritoryMgmt Namespace
TxnSecurity Namespace
UserProvisioning Namespace
VisualEditor Namespace
Appendices
Glossary
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QueryLocator Class

Represents the record set returned by Database.getQueryLocator and used with Batch Apex.

Namespace

Database

QueryLocator Methods

The following are methods for QueryLocator. All are instance methods.

getQuery()

Returns the query used to instantiate the Database.QueryLocator object. This is useful when testing the start method.

Signature

public String getQuery()

Return Value

Type: String

Usage

You cannot use the FOR UPDATE keywords with a getQueryLocator query to lock a set of records. The start method automatically locks the set of records in the batch.

Example

1System.assertEquals(QLReturnedFromStart.
2getQuery(),
3Database.getQueryLocator([SELECT Id
4   FROM Account]).getQuery() );

iterator()

Returns a new instance of a query locator iterator.

Signature

public Database.QueryLocatorIterator iterator()

Return Value

Type: Database.QueryLocatorIterator

Usage

To iterate over a query locator, save the iterator instance that this method returns in a variable and then use this variable to iterate over the collection. Calling iterator every time you want to perform an iteration can result in incorrect behavior because each call returns a new iterator instance.

Warning

For an example, see QueryLocatorIterator Class.