Question

我有一个oracle触发器：

CREATE OR REPLACE TRIGGER  "BI_Info" 
BEFORE INSERT ON "Info" FOR EACH ROW
 WHEN (NEW."Id" IS NULL OR NEW."Id" = 0) BEGIN
    SELECT NVL(MAX("Id")+1, 1) INTO :NEW."Id" FROM "Info";
END;

现在我想将它转换为ms sql触发器。

我知道[Id] [int] IDENTITY（1,1）可以类似地实现此触发器

但我不希望Id自动添加一个。

感谢。

Answer 1

MS SQL不支持BEFORE个触发器。您应该使用INSTEAD OF触发器。
MS SQL触发器是基于集合的触发器，而不是基于行的触发器，因此应该将其考虑在内

据说你可以尝试

CREATE TRIGGER tg_BI_Info_insert ON BI_Info
INSTEAD OF INSERT AS
BEGIN
  DECLARE @max INT

  SET @max = (SELECT COALESCE(MAX(id), 0) FROM BI_Info WITH (TABLOCKX, HOLDLOCK))

  INSERT INTO BI_Info (id, column1, ...)
  SELECT @max + ROW_NUMBER() OVER (ORDER BY (SELECT 1)), column1, ...
    FROM INSERTED
END

这是 SQLFiddle 演示

如果您想模拟允许插入明确指定的ID的部分WHEN (NEW."Id" IS NULL OR NEW."Id" = 0)，那么

CREATE TRIGGER tg_BI_Info_insert ON BI_Info
INSTEAD OF INSERT AS
BEGIN
  DECLARE @max INT

  INSERT INTO BI_Info
  SELECT * 
    FROM INSERTED
   WHERE COALESCE(id, 0) <> 0

  SET @max = (SELECT COALESCE(MAX(id), 0) FROM BI_Info WITH (TABLOCKX, HOLDLOCK))

  INSERT INTO BI_Info (id, column1)
  SELECT @max + ROW_NUMBER() OVER (ORDER BY (SELECT 1)), column1
    FROM INSERTED
   WHERE COALESCE(id, 0) = 0
END

此案例的 SQLFiddle 演示

将oracle触发器转换为ms sql触发器

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