Question

UPDATE PINPOINT_SUPPLEMENT
            SET (ATTACHMENT_VALUE,ATTACHMENT_TYPE) = (
            SELECT key,'file'
            FROM PINPOINT_DOCUMENT
            WHERE PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE::integer = PINPOINT_DOCUMENT.DOCUMENT_ID
            )
WHERE ATTACHMENT_VALUE IS NULL

执行此查询时出现错误

错误：“ SELECT”处或附近的语法错误第3行：SELECT键，“文件”

Answer 1

update PINPOINT_SUPPLEMENT
set
    ATTACHMENT_VALUE = PINPOINT_DOCUMENT.key,
    ATTACHMENT_TYPE = 'file'
from PINPOINT_DOCUMENT
where
    PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE::integer = PINPOINT_DOCUMENT.DOCUMENT_ID
    and PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE IS NULL

或

update PINPOINT_SUPPLEMENT
set
    (ATTACHMENT_VALUE,ATTACHMENT_TYPE) = (PINPOINT_DOCUMENT.key, 'file')
from PINPOINT_DOCUMENT
where
    PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE::integer = PINPOINT_DOCUMENT.DOCUMENT_ID
    and PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE IS NULL

Answer 2

Postgres 9.5中引入了对更新元组的支持，因此您不能在版本中使用该语法。

但是由于第二个值是一个常数，所以我看不出使用该语法开头的原因：

UPDATE PINPOINT_SUPPLEMENT
  SET ATTACHMENT_VALUE = (SELECT "key"
                          FROM PINPOINT_DOCUMENT
                          WHERE PINPOINT_SUPPLEMENT.ATTACHMENT_VALUE::integer = PINPOINT_DOCUMENT.DOCUMENT_ID), 
       ATTACHMENT_TYPE = 'file'
WHERE ATTACHMENT_VALUE IS NULL

请注意，如果ATTACHMENT_VALUE有多个document_id，则子查询可能会导致错误！

从子查询更新多列

2 个答案: