create trigger _before_insert_orders before insert on orders for each row begin declare orders goods id int; declare goods_inventory_number decimal(10,2); declare orders_goods_name varchar(50); declare msg varchar (100); if not exists (select goods name from goods where goods id=new.goods id) then setmsg-’你订购的商品不存在！请重新下订单！！ signal sqlstate '45000' set message_text=msg; end if; select inventory_number,goods_name into goods_inventory_number,orders_goods_name from goods where goods_id=new.goods_id; if goods inventory number<new.number then setmsg=concat(orders_goods_name’库存不足，请修改订购商品的数量！”; signal sqlstate '45000' set message text=msg; else update goods set inventory number=inventory number-new.number where goods id=new.goods id; end if；end 检查这段代码哪里有错

这段代码有以下几个错误：

1. `declare orders goods id int;` 这行代码有语法错误，应该是 `declare orders_goods_id int;`。

2. `setmsg-’你订购的商品不存在！请重新下订单！！ signal sqlstate '45000' set message_text=msg;` 这行代码也有语法错误，`setmsg` 应该改为 `set msg`。

3. `select inventory_number,goods_name into goods_inventory_number,orders_goods_name from goods where goods_id=new.goods_id;` 这行代码应该是 `select inventory_number,goods_name into goods_inventory_number,orders_goods_name from goods where goods_id=new.goods_id;`。

4. `setmsg=concat(orders_goods_name’库存不足，请修改订购商品的数量！”; signal sqlstate '45000' set message text=msg;` 这行代码有语法错误，应该将 `orders_goods_name` 改为 `orders_goods_name + '`，并且将 `message text` 改为 `message_text`。

修改后的代码如下：

create trigger _before_insert_orders before insert on orders for each row
begin
    declare orders_goods_id int;
    declare goods_inventory_number decimal(10,2);
    declare orders_goods_name varchar(50);
    declare msg varchar (100);
    
    if not exists (select goods_name from goods where goods_id=new.goods_id) then
        set msg='你订购的商品不存在！请重新下订单！！';
        signal sqlstate '45000' set message_text=msg;
    end if;
    
    select inventory_number,goods_name into goods_inventory_number,orders_goods_name from goods where goods_id=new.goods_id;
    
    if goods_inventory_number<new.number then
        set msg=concat(orders_goods_name, '库存不足，请修改订购商品的数量！');
        signal sqlstate '45000' set message_text=msg;
    else
        update goods set inventory_number=inventory_number-new.number where goods_id=new.goods_id;
    end if;
end;