SQL 错误：每个派生表都必须有自己的别名答案

【问题标题】：SQL Error: Every derived table must have its own aliasSQL 错误：每个派生表都必须有自己的别名
【发布时间】：2013-08-31 19:53:29
【问题描述】：

我知道有很多问题可以解决这个错误，但我已经按照他们的要求解决了我认为的问题。以下是我所做的，但我仍然收到错误。该脚本的目标是显示一定半径内的所有邮政编码。

$zip = 94550; // "find nearby this zip code"
$radius = 15; // "search radius (miles)"
$maxresults = 10; // maximum number of results you'd like

$sql = "SELECT * FROM
    (SELECT o.zipcode, o.city, o.state,
        (3956 * (2 * ASIN(SQRT(
        POWER(SIN(((z.latitude-o.latitude)*0.017453293)/2),2) +
        COS(z.latitude*0.017453293) *
        COS(o.latitude*0.017453293) *
        POWER(SIN(((z.longitude-o.longitude)*0.017453293)/2),2)
        )))) AS distance
    FROM zipcoords z,
        zipcoords o,
        zipcoords a
    WHERE z.zipcode = ".$zip." AND z.zipcode = a.zipcode AND
        (3956 * (2 * ASIN(SQRT(
        POWER(SIN(((z.latitude-o.latitude)*0.017453293)/2),2) +
        COS(z.latitude*0.017453293) *
        COS(o.latitude*0.017453293) *
        POWER(SIN(((z.longitude-o.longitude)*0.017453293)/2),2)
        )))) <= ".$radius."
    ORDER BY distance)
    ORDER BY distance ASC LIMIT 0,".$maxresults;

$result = mysql_query($sql) or die($sql."<br/><br/>".mysql_error());   

while ($ziprow = mysql_fetch_array($result)) {
$zipcode = $ziprow['zipcode'];
echo "$zipcode<br>";
}

我在数据库中的所有列都是 varchar。邮政编码是主要的，我会将其设为 INT，但它不允许在邮政编码的开头有 0。所以我将其更改为 varchar 并且它允许它。感谢您的帮助！

【问题讨论】：

标签： php mysql sql zipcode

【解决方案1】：

$sql = "SELECT * FROM
    (SELECT o.zipcode, o.city, o.state,
        (3956 * (2 * ASIN(SQRT(
        POWER(SIN(((z.latitude-o.latitude)*0.017453293)/2),2) +
        COS(z.latitude*0.017453293) *
        COS(o.latitude*0.017453293) *
        POWER(SIN(((z.longitude-o.longitude)*0.017453293)/2),2)
        )))) AS distance
    FROM zipcoords z,
        zipcoords o,
        zipcoords a
    WHERE z.zipcode = ".$zip." AND z.zipcode = a.zipcode AND
        (3956 * (2 * ASIN(SQRT(
        POWER(SIN(((z.latitude-o.latitude)*0.017453293)/2),2) +
        COS(z.latitude*0.017453293) *
        COS(o.latitude*0.017453293) *
        POWER(SIN(((z.longitude-o.longitude)*0.017453293)/2),2)
        )))) <= ".$radius."
    ORDER BY distance) AS random_word_to_silence_that_error
    ORDER BY distance ASC LIMIT 0,".$maxresults;

我添加了random_word_to_silence_that_error，因为在您的情况下，我认为它不会有其他用途。

【讨论】：

【解决方案2】：

在选择FROM a子查询时是强制性的。

见：http://dev.mysql.com/doc/refman/5.0/en/from-clause-subqueries.html

只需在要从中选择的子查询末尾添加AS <alias name>：

...
ORDER BY distance) AS SOME_ALIAS
ORDER BY distance ASC LIMIT 0
...

【讨论】：