SIGMOD: ACM SIGMOD Conf on Management of Data
       PODS: ACM SIGMOD Conf on Principles of DB Systems
       VLDB: Very Large Data Bases
       ICDE: Intl Conf on Data Engineering

       CIKM: Intl. Conf on Information and Knowledge Management
       ICDT: Intl Conf on Database Theory

Rank 2:

SSD: Intl Symp on Large Spatial Databases
DEXA: Database and Expert System Applications
FODO: Intl Conf on Foundation on Data Organization
EDBT: Extending DB Technology
DOOD: Deductive and Object-Oriented Databases
DASFAA: Database Systems for Advanced Applications
SSDBM: Intl Conf on Scientific and Statistical DB Mgmt
CoopIS - Conference on Cooperative Information Systems
ER - Intl Conf on Conceptual Modeling (ER)

参考 http://www3.ntu.edu.sg/home/assourav/crank.htm