set sender_id = (选择存在(从account
中选择 1,其中 account_id = p_sender_id));
设置 viewer_id = (选择存在(从account
中选择 1,其中 account_id = p_viewer_id));
你可以做这样的事情:
SELECT EXISTS(SELECT 1 FROM account WHERE account_id = p_sender_id)),
EXISTS(SELECT 1 FROM account WHERE account_id = p_viewer_id))
INTO sender_id, viewer_id;
阅读更多关于选择...到。
重新发表您的评论:
如果要运行一个子查询来设置两者:
SELECT
MAX(CASE account_id WHEN p_sender_id THEN 1 ELSE 0 END),
MAX(CASE account_id WHEN p_viewer_id THEN 1 ELSE 0 END)
INTO sender_id, viewer_id
FROM account
WHERE account_id IN (p_sender_id, p_viewer_id);