Question

我有一个MySQL查询问题。我建了一张能够追踪高中足球比分的桌子。它看起来像这样：

CREATE TABLE `games` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `home_team` int(11) NOT NULL,
  `visitor_team` int(11) NOT NULL,
  `home_score` tinyint(4) NOT NULL,
  `visitor_score` tinyint(4) NOT NULL,
  `quarter` tinyint(4) NOT NULL,
  `week` tinyint(2) NOT NULL,
  `game_date` date NOT NULL,
  `game_time` time NOT NULL,
  `complete` tinyint(4) NOT NULL DEFAULT '0',
  `stadium_id` int(11) NOT NULL,
  `created_at` datetime NOT NULL,
  `updated_at` datetime NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=151;

我正在进行的查询使用团队的ID进行比较。我想检索给定团队ID仅被击败的团队的id值。到目前为止，这是我的查询。

SELECT 
    CASE 
        WHEN games.home_team != ? AND (games.home_score > games.visitor_score) THEN games.home_team 
        WHEN games.visitor_team != ? AND (games.home_score < games.visitor_score) THEN games.visitor_team 
    END AS id, teams.class_id, classes.name 
FROM games 
    INNER JOIN teams ON id = teams.id 
    INNER JOIN classes ON teams.class_id = class.id
    WHERE games.complete = 1

当我在PHP MyAdmin中运行此查询时，出现以下错误：

#1052 - Column 'id' in on clause is ambiguous

我正在使用PDO的execute（），因此？代表团队ID值。我想，因为我将我的CASE语句的结果分配给id，然后我可以用它来加入团队表。有人能指出我正确的方向来修复这个错误吗？提前谢谢。

Answer 1

您需要在多个表中的列前面使用表名，或使用别名：

INNER JOIN teams ON games.id = teams.id

编辑：话虽如此，它似乎实际上是一个列别名，你不能这样做：

INNER JOIN teams ON
CASE 
    WHEN games.home_team != ? AND (games.home_score > games.visitor_score) THEN games.home_team 
    WHEN games.visitor_team != ? AND (games.home_score < games.visitor_score) THEN games.visitor_team 
END  = teams.id

您也可以先使用子查询，然后匹配结果而不使用额外的case语句。

Select
    sub.id,
    teams.class_id,
    classes.name
from
    (
        SELECT 
            CASE 
            WHEN games.home_team != ? AND (games.home_score > games.visitor_score) THEN games.home_team 
            WHEN games.visitor_team != ? AND (games.home_score < games.visitor_score) THEN games.visitor_team 
            END AS id
        FROM 
            games
        WHERE 
            games.complete = 1
    ) sub
    INNER JOIN teams ON sub.id = teams.id 
    INNER JOIN classes ON teams.class_id = class.id

Answer 2

我做了一个简单的功能。它正在运作。

// get variable
$area = $_GET['area'];

// function
function cases($a) {

    $sel_dash = mysql_query("SELECT * FROM sys_dash WHERE area = '$a'");
    $dados = mysql_fetch_assoc($sel_dash);
    $page = $dados['page'];

    return $page;
}

// call function with the variable
$page = cases($area);

要测试您获得的值是否正确，您可以将“return”更改为“echo”，并且该变量将写入代码中。

我使用的表是：

CREATE TABLE `sys_dash` (
    `id` INT(10) NOT NULL AUTO_INCREMENT,
    `area` VARCHAR(250) NOT NULL,
    `page` VARCHAR(250) NOT NULL,
    PRIMARY KEY (`id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB
ROW_FORMAT=DEFAULT

我希望我能帮忙！

它注意到PHP的CASE类，但具有我需要的相同功能。

由于

Doniani

SELECT中的MySQL CASE语句

2 个答案: