@是什么! From语句中的均值 [英] What does @ ! mean in a From Statement
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问题描述
我正在尝试确定此代码的作用(Oracle SQL),尤其是from
子句中的符号感叹号.
I am trying to determine what this code is doing (Oracle SQL) — especially the at-sign exclamation mark in the from
clause.
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")
推荐答案
这是指向执行查询的原始数据库的反向数据库链接.原始查询必须类似于:
This is a reverse database link to the original database, where the query is executed. The original query must look like:
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,而本地表通过"@!"变为远程表.
That way all remote tables become local, and local tables become remote with "@!".
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