无法确定在 MySQL 中创建存储过程的语法问题

Question

我正在尝试创建以下存储过程 (XAMPP > phpMyAdmin)：

        DROP PROCEDURE IF EXISTS changeTurn;
        
        DELIMITER //
        
        create procedure changeTurn(in currentGameID bigint(20))
        begin
            declare turnHasBeenChanged tinyint(1) default 0
            
            select @targetPlayer := player_number from game_players where gameID = currentGameID and current_turn = 1

            set @targetPlayer = @targetPlayer + 1

            update game_players set current_turn = 0 where gameID = currentGameID and current_turn = 1

            while turnHasBeenChanged = 0 do
                case
                    when @targetPlayer > 4
                    then set @targetPlayer = 1
                end
                case
                    when (select forfeit_next_turn from game_players where gameID = currentGameID and player_number = @targetPlayer) = 1
                    then
                    update game_players set forfeit_next_turn = 0 where gameID = currentGameID and player_number = @targetPlayer
                    set @targetPlayer = @targetPlayer + 1
                    else
                    update game_players set current_turn = 1 where gameID = currentGameID and player_number = @targetPlayer
                    set turnHasBeenChanged = 1
                end
            end while
        end
        
        end //
        DELIMITER ;

无论有没有分隔符，我都会遇到以下问题：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'select @targetPlayer := player_number from game_players where gameID = curren...' at line 5

很遗憾，这不是很具体。

在将这个过程拼凑在一起时，我确保我对每个部分都使用了正确的语法。但现在它完全，它很无聊。请你能给我一些关于为什么会出错的方向吗？

我检查了第 4 行（声明 turnHasBeenChanged tinyint(1) 默认为 0），以防它的语法导致后续行失败，并在其末尾添加了一个分号，并在该行中断了它，所以不是那样的。

然后我根据https://www.oreilly.com/library/view/mysql-cookbook/0596001452/ch01s15.html 验证了第 5 行的语法，它似乎是正确的...？

Answer 1

每个命令都必须以 ; 结尾

还有什么时候应该用 IF THEN 来代替

最后，你有很多事情要结束

所以以下不再给出错误

    DROP PROCEDURE IF EXISTS changeTurn;
    
    DELIMITER //
    
    create procedure changeTurn(in currentGameID bigint(20))
    begin
        declare turnHasBeenChanged tinyint(1) default 0;
        
        select @targetPlayer := player_number from game_players where gameID = currentGameID and current_turn = 1;

        set @targetPlayer = @targetPlayer + 1;

        update game_players set current_turn = 0 where gameID = currentGameID and current_turn = 1;

        while turnHasBeenChanged = 0 do
            IF @targetPlayer > 4
                then set @targetPlayer = 1;
            end IF;
            IF ((select forfeit_next_turn from game_players where gameID = currentGameID and player_number = @targetPlayer) = 1)
                then
                update game_players set forfeit_next_turn = 0 where gameID = currentGameID and player_number = @targetPlayer;
                set @targetPlayer = @targetPlayer + 1;
                else
                update game_players set current_turn = 1 where gameID = currentGameID and player_number = @targetPlayer;
                set turnHasBeenChanged = 1;
            end IF;
        end while;
    
    end //
    DELIMITER ;