Shuduo Sang 4281e3a5e7 change null to NULL according to Dr. Liao		2020-05-08 10:35:14 +08:00
..
metrics.sim	change null to NULL according to Dr. Liao	2020-05-08 10:35:14 +08:00
table.sim	change null to NULL according to Dr. Liao	2020-05-08 10:35:14 +08:00