Question

我刚刚将node.js应用程序上传到heroku，我的一个SQL查询失败了。查询是：

INSERT INTO countries (name, user_id, created_timestamp)
SELECT $1, $2, CURRENT_TIMESTAMP
WHERE NOT EXISTS (SELECT 1 FROM countries WHERE name = $1 FOR UPDATE)

失败

错误：子查询中不允许SELECT FOR UPDATE / SHARE

有谁知道为什么？如果我无法选择更新，我可以使用吗？

Answer 1

这可能对您有用：

BEGIN;

LOCK TABLE countries IN SHARE MODE;

INSERT INTO countries (name, user_id, created_timestamp)
SELECT $1, $2, CURRENT_TIMESTAMP
WHERE NOT EXISTS (SELECT * FROM countries WHERE name = $1);

COMMIT;

Explanation and links in this closely related answer.

关于heroku sql语句的postgres失败

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