Mysql 存储过程sql语法错误

数据库中有5个表

ApartamentClass(idclass,descript)
Room(idroom,idclass,beds,isfree)
ItemPrice(iditem,idclass,description,price)
Client(idclient,fio)
Active(idcontract,idclient,idroom,days,price,idclass)

我需要创建一个存储过程，检查是否存在具有特定类别

（param1）

和床位数

（param2）

的免费房间，并为该房间和客户（fio）

（param3）

创建几天的租赁合同

（param4）

。 价格取决于房间的等级（更高的等级->一张床和一天的更高价格）

但我总是发现SQL语法错误。我不知道问题出在哪里。

您的SQL语法有错误；检查与您的MySQL服务器版本对应的手册，以了解在“declare iclient int default 0”附近使用的正确语法；
从客户端将idclient选择到iclient
第20行的所有DECLARE语句必须位于BEGIN的开头。。。此处MySQL文档中所述的结束块：

仅允许在BEGIN中声明。。。结束复合语句，并且必须在其开始处，在任何其他语句之前

因此，您可能需要尝试以下代码：

create procedure UserRequest(
    in param1 int,
    in param2 int,
    in param3 varchar(100),
    in param4 int
)
begin   
    declare iroom int default 0;
    declare iclient int default 0;
    declare bedprice decimal default 0.0;
    declare dayprice decimal default 0.0;
    declare price decimal default 0.0;

    select idroom into iroom from room
    where beds = param2 and idclass = param1 and isfree = 0
    limit 1;


    if not (iroom=0) then
        update room set isfree = 1
        where idroom = iroom;
    end if;


    select idclient into iclient from client
    where fio = param3
    limit 1;

    select (param2 * price) into bedprice from itemprice
    where description = "bed" and idclass = param1;

    select (param4 * price) into dayprice from itemprice
    where description = "day" and idclass = param1;

    set price = bedprice + dayprice;


    insert into active(idclient,idroom,days,price,idclass)
    values(iclient,iroom,param4,price,param1);
end

是的，它有效！但为什么
声明的位置在MySQL中很重要呢？
create procedure UserRequest(
    in param1 int,
    in param2 int,
    in param3 varchar(100),
    in param4 int
)
begin   
    declare iroom int default 0;
    declare iclient int default 0;
    declare bedprice decimal default 0.0;
    declare dayprice decimal default 0.0;
    declare price decimal default 0.0;

    select idroom into iroom from room
    where beds = param2 and idclass = param1 and isfree = 0
    limit 1;


    if not (iroom=0) then
        update room set isfree = 1
        where idroom = iroom;
    end if;


    select idclient into iclient from client
    where fio = param3
    limit 1;

    select (param2 * price) into bedprice from itemprice
    where description = "bed" and idclass = param1;

    select (param4 * price) into dayprice from itemprice
    where description = "day" and idclass = param1;

    set price = bedprice + dayprice;


    insert into active(idclient,idroom,days,price,idclass)
    values(iclient,iroom,param4,price,param1);
end