sql - @! 是什么意思？在 From 语句中的意思

Question

我试图确定这段代码在做什么（Oracle SQL）——尤其是子句中的at-sign 感叹号。from

INSERT INTO "LOCATIONS" "A1"
            ("LOCATION_ID",
             "SEQUENCE",
             "POINT_TYPE")
SELECT "A2"."LOCATION_ID",
       "A2"."SEQUENCE",
       "A2"."LOCATION_TYPE",
       "A2"."POINT_TYPE"
FROM   "LOCATIONS"@! "A2"
WHERE  NOT EXISTS (SELECT 1
                   FROM   "LOCATIONS" "A3"
                   WHERE  "A3"."LOCATION_ID" = "A2"."LOCATION_ID") 

Answer 1

这是到执行查询的原始数据库的反向数据库链接。原始查询必须如下所示：

INSERT INTO LOCATIONS@remote_db
            ("LOCATION_ID",
             "SEQUENCE",
             "POINT_TYPE")
SELECT "A2"."LOCATION_ID",
       "A2"."SEQUENCE",
       "A2"."POINT_TYPE"
FROM   "LOCATIONS" A2
WHERE  NOT EXISTS (SELECT 1
                   FROM   LOCATIONS@remote_db A3
                   WHERE  "A3"."LOCATION_ID" = "A2"."LOCATION_ID");

这样，所有远程表都变为本地表，本地表变为远程“@！”。

Answer 2

我认为这不是有效的 SQL。检查您的代码以确保在执行 SQL 之前没有任何更改 - 特别是检查数据库链接的名称是否被替换为!.

如果您无法确定正在执行的内容，您可以在数据库上进行跟踪