给定如下代码: CREATE TABLE tb_account(num INT, amount DECIMAL(10,2)); CREATE TRIGGER tr_acct AFTER INSERT ON tb_account FOR EACH ROW SET @sum=@sum+NEW.amount; 表和触发器成功创建后,执行如下命令: SET @sum=0.00; INSERT INTO tb_account VALUES(1,7.00); INSERT INTO tb_account VALUES(2,3.00); 上述代码执行成功后@sum的值为( )。