tsql - Out 参数被正确分配，但调用者只看到一个 NULL。线索？

Question

我有这个过程作为 T-SQL 脚本的一部分被删除/创建 - 想法是插入父记录，并将其 ID 输出给调用者，以便我可以使用该 ID 插入子记录。

if exists (select * from sys.procedures where name = 'InsertCategory')
    drop procedure dbo.InsertCategory;
go

create procedure dbo.InsertCategory
     @code nvarchar(5)
    ,@englishName nvarchar(50)
    ,@frenchName nvarchar(50)
    ,@timestamp datetime = null
    ,@id int output
as begin

    if @timestamp is null set @timestamp = getdate();

    declare @entity table (_Id int, EntityId uniqueidentifier);
    declare @entityId uniqueidentifier;

    if not exists (select * from dwd.Categories where Code = @code)
    insert into dwd.Categories (_DateInserted, Code, EntityId) 
        output inserted._Id, inserted.EntityId into @entity
        values (@timestamp, @code, newid());
    else
        insert into @entity
        select _Id, EntityId from dwd.Categories where Code = @code;

    set @id = (select _Id from @entity);
    set @entityId = (select EntityId from @entity);

    declare @english int;
    set @english = (select _Id from dbo.Languages where IsoCode = 'en');

    declare @french int;
    set @french = (select _Id from dbo.Languages where IsoCode = 'fr');

    exec dbo.InsertTranslation @entityId, @english, @englishName, @timestamp;
    exec dbo.InsertTranslation @entityId, @french, @frenchName, @timestamp;

end
go

然后再往下一点，它被称为这样的脚本:

declare @ts datetime;
set @ts = getdate();

declare @categoryId int;

exec dbo.InsertCategory 'C1', 'Category1', 'Catégorie1', @ts, @categoryId;
exec dbo.InsertSubCategory 'SC1', @categoryId, 'Description (EN)', 'Description (FR)', @ts

当我调试脚本并逐行执行时，我可以看到 dbo.InsertCategory正确分配 @id out 参数，脚本将其视为 @categoryId - 问题是 @categoryId总是 null ，所以我没有在 dwd.SubCategories 中插入任何内容.

我究竟做错了什么？

Answer 1

您需要提及@categoryId参数为 OUTPUT在调用过程时，它不会返回值。像这样调用程序

exec dbo.InsertCategory 'C1', 'Category1', 'Catégorie1', @ts, @categoryId OUTPUT;

示例

CREATE PROCEDURE Procd (@a INT, @b INT output)
AS
  BEGIN
      SELECT @b = @a
  END

DECLARE @new INT

EXEC Procd 1,@new 
SELECT @new -- NULL

EXEC Procd 1,@new OUTPUT 
SELECT @new -- 1