Need to add public group when Permission set group assigned to the Salesforce user using custom metadata approach via scheduled job Need working code

Suppose there is one user in salesforce for that user we need to assign public group when PSG gets assign to that user similar kind of Public Group need to assign     I created custom meta data where added field Public group(keeping id), PSG Id (keeping PSG id) for mapping     So while querying User if PSG is assigned it should match in custom metadata approach via data for that Public group and add that public for that user