Sorry if this question have been asked before . Why SqlQueryBuilder class is used in ContentProvider 
1) For what purpose SqlQueryBuilder class is used for ?
2) what this method does?
 qb.setTables(STUDENTS_TABLE_NAME);
 qb.setProjectionMap(STUDENTS_PROJECTION_MAP);
 qb.appendWhere( _ID + "=" + uri.getPathSegments().get(1));
3) I noticed in content resolver that to call content provider query().managedQuery() is used . Why this method is used?