Sybase更新触发 - 检查多行以进行更新

Question

我正在在Sybase ASE数据库中编写触发器，该数据库在更新时发射并比较更新之前和之后的值。我这样做是为了验证更新是否实际更改了数据。如果是这种情况，它会将行添加到监视表。不幸的是，如果update命令只影响1行，则触发器仅适用。如果它影响多于一行，我会收到此错误：

Msg 512, Level 16, State 5:
Server 'myserver', Procedure 'myproc', Line 2:
Subquery returned more than 1 value.  This is illegal when the subquery follows =, !=, <, <= , >, >=, or when the subquery is used as an expression.

.

我的proc看起来如此：

create trigger mytrigger on mytable for update as

set nocount on

/* now do the insert if colum was updated  */
if update(col_a) and (select col_a from inserted) not in (select col_a from deleted) 
begin
    insert into monitoring_table (login,tablename,field,action,pstamp) 
        select suser_name(),'mytable','col_a','U',getdate() from inserted
end
/* now do the insert if colum was updated  */
if update(col_b) and (select col_b from inserted) not in (select col_b from deleted) 
begin
    insert into monitoring_table (login,tablename,field,action,pstamp) 
        select suser_name(),'mytable','col_b','U',getdate() from inserted
end
go

.

任何想法如何在我的触发器中绕过这个多更新问题？

Answer 1

如果错误在触发器中，则以下应工作： 而不是：

if update(col_a) and (select col_a from inserted) not in (select col_a from deleted)

.

使用

if update(col_a) and exists (select col_a from inserted where col_a not in (select col_a from deleted))

.

Answer 2

这应该有效：

create trigger mytrigger on mytable for update as

set nocount on

/* now do the insert if colum was updated  */
if update(col_a) and (select col_a from inserted where col_a not in (select col_a from deleted) 
begin
    insert into monitoring_table (login,tablename,field,action,pstamp) 
        select suser_name(),'mytable','col_a','U',getdate() from inserted
end
/* now do the insert if colum was updated  */
if update(col_b) and (select col_b from inserted where col_b not in (select col_b from deleted) 
begin
    insert into monitoring_table (login,tablename,field,action,pstamp) 
        select suser_name(),'mytable','col_b','U',getdate() from inserted
end
go

.