mysql查询主键

 SELECT column_name
  FROM INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` 
 WHERE table_name='sys_user' 
 AND CONSTRAINT_SCHEMA='ulab'
 AND constraint_name='PRIMARY'

 SELECT column_name
  FROM INFORMATION_SCHEMA.`KEY_COLUMN_USAGE` 
 WHERE table_name='表明' 
 AND CONSTRAINT_SCHEMA='数据库'
 AND constraint_name='PRIMARY'