假设你有一个主键列，id，(你应该有一个主键)，加入插入表(使触发器能够处理多行):

Assuming you have a primary key column, id, (and you should have a primary key), join to the inserted table (making the trigger capable of handling multiple rows):

CREATE TRIGGER tUpdateColB 
ON products 
FOR INSERT, UPDATE AS 
    BEGIN 
        UPDATE table 
        SET t.columnB = i.columnA 
        FROM table t INNER JOIN inserted i ON t.id = i.id
    END 

但如果 ColumnB 始终是 ColumnA 的副本，为什么不创建一个 计算列 代替?

But if ColumnB is always a copy of ColumnA, why not create a Computed column instead?

使用插入和删除的表