sql-server - 如果没有游标或循环，我怎么能做到这一点？

Question

我听说要使用声明式编程，但我不知道如何在 sql server 2005 中做这样的事情（我输入得非常快，所以我不确定所有语法是否正确，但我想你会明白我的意思米找）

declare curs cursor for
select @Name, @Description, @Id FROM TableA
open curs
while(1=1) 
begin
    fetch next from curs into
        @Name,
        @Description,
        @Id
    if(@@fetch_status<>0) break

    set @recordCount = (SELECT COUNT(*) As RecordCount FROM Class1 WHERE          
            Class1Id = @Id)
    if(@recordCount > 0)
    begin

        if(@Name = 'BAD NAME') CONTINUE
        UPDATE Class1 SET 
            Name = @Name
            , Description = @Description
            WHERE Class1Id = @Id
    end
    else
    begin
        INSERT INTO Class1 (Class1Id, Name, Description)
        VALUES (@Id, @Name, @Description)
    end

end
close curs
deallocate curs

Answer 1

UPDATE Class1 
SET Name = t.Name, 
Description = t.Description
FROM Class1 c 
JOIN TableA t ON c.id=t.id
WHERE t.name <> 'BAD NAME'

INSERT INTO Class1 (Class1Id, Name, Description)
select t.Id, t.Name, t.Description
FROM TableA t
LEFT JOIN Class1  c on t.id=c.id
where c.id IS NULL