Getting Childrelationships from an object using dynamic Apex

If an sObject is a parent object, you can access the child relationship as well as the child sObject using the ChildRelationship object methods.

A ChildRelationship object is returned from the sObject describe result using the getChildRelationship method. For example:

Schema.DescribeSObjectResult   describeresult = Account.SObjectType.getDescribe();//it gives Account  object properties or describe results

List<Schema.ChildRelationship>   lstchildrelationships =describeresult.getChildRelationships(); //It gives you all the childrelationships associated with the account.

To get relationship names from the above list

for(Schema.ChildRelationship relname:lstchildrelationships){

      System.debug('Relationshipname:'+relname.getrelationshipname();

}

Limitation:

You can only use 100getChildRelationships method calls per Apex request.

The following table describes the methods available as part of the ChildRelationship object. None of the methods take an argument.

Name	Data Type	Description
getChildSObject	Schema.SObjectType	Returns the token of the child sObject on which there is a foreign key back to the parent sObject.
getField	Schema.SObjectField	Returns the token of the field that has a foreign key back to the parent sObject.
getRelationshipName	String	Returns the name of the relationship.
isCascadeDelete	Boolean	Returns true if the child object is deleted when the parent object is deleted, false otherwise.
isDeprecatedAndHidden	Boolean	Reserved for future use.
isRestrictedDelete	Boolean	Returns true if the parent object can't be deleted because it is referenced by a child object, false otherwise.