def execute(self, conn, data_tier_name='', transaction = False, cache=None):
        """
        returns id for a given datatier name
        """
	if cache:
            ret=cache.get("DATA_TIERS")
            if not ret==None:
                return ret
        sql = self.sql
	binds={}
	if data_tier_name:
            op = ('=', 'like')['%' in data_tier_name]
	    sql += "WHERE DT.DATA_TIER_NAME %s :datatier" %op 
	    binds = {"datatier":data_tier_name}
        result = self.dbi.processData(sql, binds, conn, transaction)
        plist = self.formatDict(result)
        return plist
returns id for a given datatier name