从2数据库中选择删除同一列

Question

我需要从第一个数据库中选择第2个数据库中表2中不存在的表1的所有值。我尝试了下面的代码，但DISTINCT不起作用：

select DISTINCT(affected_ci),ci_name from sitequota.incidents,appwarehouse.ci_table where incidents.affected_ci <> ci_table.ci_name


DATABASE1: APPWAREHOUSE
TABLE1:    CI_TABLE
COLUMN:    CI_NAME


DATABASE2:  SITEQUOTA
TABLE2:     INCIDENTS
COLUMN:     AFFECTED_CI

Answer 1

您可以尝试以下方式：

SELECT ci_name
FROM appwarehouse.ci_table
WHERE ci_name NOT IN
  (SELECT affected_ci FROM sitequota.incidents
  )