Question

我希望Wordpress查询中有一个foreach。

$aid=0;
    foreach ($QA as $key => $value) {
    AND wp_postmeta.post_id IN (
        SELECT wp_postmeta.post_id
        FROM wp_postmeta, wp_posts
        WHERE wp_posts.ID = wp_postmeta.post_id
        AND wp_posts.post_status = 'publish'
        AND wp_posts.post_type = 'post'
        AND wp_postmeta.meta_key = '$key'
        AND wp_postmeta.meta_value = '$value'
    )
    $aid++;
}

但它没有那样工作，所以我在寻求帮助 -

如何将foreach放入sql查询？

以下代码的完整示例。

<?php
 function query_products($QA) {

global $wpdb;
global $post;
global $pageposts;

$querystr = "

SELECT wp_posts.*, wp_postmeta.*
FROM wp_postmeta, wp_posts
WHERE wp_posts.ID = wp_postmeta.post_id
AND wp_posts.post_status = 'publish'
AND wp_posts.post_type = 'post'
AND wp_postmeta.meta_key = 'country'
AND wp_postmeta.meta_value = 'Denmark'

$aid=0;
    foreach ($QA as $key => $value) {
    AND wp_postmeta.post_id IN (
        SELECT wp_postmeta.post_id
        FROM wp_postmeta, wp_posts
        WHERE wp_posts.ID = wp_postmeta.post_id
        AND wp_posts.post_status = 'publish'
        AND wp_posts.post_type = 'post'
        AND wp_postmeta.meta_key = '$key'
        AND wp_postmeta.meta_value = '$value'
    )
    $aid++;
}

ORDER BY wp_postmeta.meta_value ASC 
    ";

$pageposts = $wpdb->get_results($querystr, OBJECT);

}

$QA = array (
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => 'value3',
);
query_products($QA);
?>

Answer 1

$querystr = "
SELECT wp_posts.*, wp_postmeta.*
FROM wp_postmeta, wp_posts
WHERE wp_posts.ID = wp_postmeta.post_id
AND wp_posts.post_status = 'publish'
AND wp_posts.post_type = 'post'
AND wp_postmeta.meta_key = 'country'
AND wp_postmeta.meta_value = 'Denmark'
";

$aid=0;
    foreach ($QA as $key => $value) {
       $querystr .= "
    AND wp_postmeta.post_id IN (
        SELECT wp_postmeta.post_id
        FROM wp_postmeta, wp_posts
        WHERE wp_posts.ID = wp_postmeta.post_id
        AND wp_posts.post_status = 'publish'
        AND wp_posts.post_type = 'post'
        AND wp_postmeta.meta_key = '$key'
        AND wp_postmeta.meta_value = '$value'";
    )
    $aid++;
}
$querystr .=" ORDER BY wp_postmeta.meta_value ASC";

Answer 2

在不知道查询应该完成什么的情况下，我只能建议这样的事情：

<?php

$querystr = "
SELECT wp_posts.*, wp_postmeta.*
FROM wp_postmeta, wp_posts
WHERE wp_posts.ID = wp_postmeta.post_id
AND wp_posts.post_status = 'publish'
AND wp_posts.post_type = 'post'
AND wp_postmeta.meta_key = 'country'
AND wp_postmeta.meta_value = 'Denmark'
AND wp_postmeta.post_id IN (
    SELECT wp_postmeta.post_id
    FROM wp_postmeta, wp_posts
    WHERE wp_posts.ID = wp_postmeta.post_id
    AND wp_posts.post_status = 'publish'
    AND wp_posts.post_type = 'post'
";
if (count($QA) >= 1) {
    $querystr .= " AND ( ";
    foreach($QA as $key => $value) {
        $querystr .= "(wp_postmeta.meta_key = '{$key}' AND wp_postmeta.meta_value = '{$value}') OR ";
    }
    // get rid of the last "OR" in the string
    $querystr = substr($querystr,0,strrpos($querystr,"OR"));
    $querystr .= " ) ";
}
$querystr .= " ORDER BY wp_postmeta.meta_value ASC ";

?>

注意我上面使用了“OR”，因为在使用“AND”子句检查单个字段的多个值时，您永远不会得到任何结果。

Answer 3

您需要将所有键作为数组传递或迭代地发出完整查询（包括选择）。我不推荐后者，因为性能会很差（过多的数据库往返都很糟糕）。所以，只要$ QA不是太大，我就会这样做。我认为它比使用EXISTS条款最初提交的完整子查询更简单，但这可能更像是一种品味，而不是真正优于另一种。

<?php
 function query_products($QA) {

global $wpdb;
global $post;
global $pageposts;

    $querystr = "
    SELECT wp_posts.*, wp_postmeta_a.*
    FROM wp_postmeta AS wp_postmeta_a, wp_posts, wp_postmeta AS wp_postmeta_b
    WHERE wp_posts.ID = wp_postmeta_a.post_id
    AND wp_posts.post_status = 'publish'
    AND wp_posts.post_type = 'post'
    AND wp_postmeta_a.meta_key = 'country'
    AND wp_postmeta_a.meta_value = 'Denmark'
    ";

    $aid=0;
    foreach ($QA as $key => $value) {
        $querystr .= "
            AND EXISTS (SELECT 1
                    FROM wp_postmeta AS wp_postmeta_b
                    WHERE wp_posts.ID = wp_postmeta_b.post_id
                    AND wp_postmeta_b.meta_key = '$key'
                    AND wp_postmeta_b.meta_value = '$value')
        ";

        $aid++;
    }

    $querystr .= " ORDER BY wp_postmeta_a.meta_value ASC ";


    $pageposts = $wpdb->get_results($querystr, OBJECT);

}

$QA = array (
    'key1' => 'value1',
    'key2' => 'value2',
    'key3' => 'value3',
);
query_products($QA);
?>

查询Foreach内部

3 个答案: