I have picklist value on the account object yes/no. If the value of picklist in parent record is updated as yes then it should update child records with some message. Can anyone help how to approach it??
You can use the declarative approach in Salesforce and create a workflow rule. You can find read about them here.
A rough format for the workflow rule will be:
ISPICKVAL(YourObject.YourPickList , "Yes")
Then when the workflow evaluates to true you need to select the option of field update. Have a look here on how to define a field update.
Hope it helps
You should be able to create a cross object formula and conditionally display the message based on the value of the parent account.
Cross-object formulas are formulas that span two related objects and reference merge fields on those objects. Cross-object formulas can reference merge fields from a master (“parent”) object if an object is on the detail side of a master-detail relationship. You can reference fields from objects that are up to 10 relationships away. Cross-object formulas are available anywhere formulas are used except when creating default values.
Many ways of doing this without using the code. Depends if you want the contact OBJ to pull the value from the account, or the account to push the value to its child contacts.
You could use formula field on contact to pull the value. You could use process builder to push the value from account.