PostgreSQL：不存在則INSERT，存在則返回ID

Question

以下查詢插入 IP 地址（如果沒有）並返回 ID。

WITH variables AS (
  SELECT '1.1.1.2'::inet AS ip
)
INSERT INTO globals.ips (ip)
SELECT v.ip
FROM variables AS v
WHERE NOT EXISTS (
    SELECT i.global_ip_id 
    FROM globals.ips AS i 
    WHERE i.ip = v.ip
)
RETURNING global_ip_id

但是，當該值已存在於數據庫中時，它不會返回 ID。

當值已經存在時，如何獲取 ID？

---

我正在運行 PostgreSQL 12。

Answer 1

WITH variables AS (
  SELECT '1.1.1.2'::inet AS ip
), wt0 as (
INSERT INTO globals.ips (ip)
SELECT v.ip
FROM variables AS v
WHERE NOT EXISTS (
    SELECT i.global_ip_id 
    FROM globals.ips AS i 
    WHERE i.ip = v.ip
)
RETURNING global_ip_id
)
SELECT global_ip_id FROM wt0
UNION
SELECT id FROM globals.ips WHERE ip = 'SOMETHING';

Answer 2

我不確定這是最優雅的； 但它每次都會返回 IP 的 ID。 而我只需要輸入一次IP。

WITH v AS (
   SELECT '1.1.1.110'::inet AS ip
), i AS (
    INSERT INTO globals.ips (ip)
    SELECT * FROM v
    WHERE NOT EXISTS (
        SELECT i.global_ip_id
        FROM globals.ips AS i
        WHERE i.ip = v.ip
    )
    RETURNING global_ip_id
)
SELECT global_ip_id FROM i
UNION ALL
SELECT global_ip_id FROM globals.ips g
LEFT JOIN v ON g.ip = v.ip
WHERE g.ip = v.ip
LIMIT 1;

如果有人對如何改進這一點有任何建議，請告訴我。

---

更優雅的解決方案：

INSERT INTO globals.ips (ip) VALUES ('1.1.1.1'::inet)
ON CONFLICT (ip) DO UPDATE SET ip = EXCLUDED.ip
RETURNING global_ip_id AS id;

但是，比原來的慢一點。