postgres on heroku sql语句失败

Question

我刚刚上传了我的node.js应用程序到heroku上，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) 

它与

失败

error: SELECT FOR UPDATE/SHARE is not allowed in subqueries

有谁知道为什么吗？如果我无法选择更新，是否有可以使用的解决方法？

Answer 1

这可能会为你工作：

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.